Editing Portal/Chamber 18

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Chamber 18 is the hardest test chamber yet in Portal. I hope you have your fingers (and your in-screen portal gun) ready! Chamber 18 is cold, a bit inhuman, and a bit scary, but it's quite fun. Chamber 18 has a lot of tough challenges, but look on the bright side: you might get cake after you complete the next chamber!
{{quote|The Enrichment Center is required to remind you that you will be baked, and then there will be cake.|GLaDOS}}
{{Achievement|name=[[Portal/Camera Shy|Camera Shy]]|image=Portal_achievement_camera_shy.jpg|progress=30|total=33|description=There are 2 accessible cameras:
#Next to the window at the entrance of the turret room.
#On the wall of the entrance of the final room.}}
Well... maybe...

== Walkthrough ==
=== Part 1 - Drops and Flings ===
{{Achievement|name=[[Portal/Transmission_Received|Transmission Received]]|image=Portal achievement Transmission Received.jpg|width=350px|description=You will find the first radio in the side room after the first gap. It can be tough [[Portal/Tips and advanced techniques#Flinging with an object|getting the radio onto the next platform]], but once you do, stand on the platform labeled with 2 dots in such a way that looking as far down as you can, you’re looking at the center of that white square. Now look straight up as far as you can and place a portal. Either fall through, or simply send the radio through, and you’ve got it.|progress=20|total=26}}
[[File:Portal_Chamber_18_first_step_portals.png|thumb|left|Your first two portals.]]
Lethal water to take note of here! To get past the lethal gap, put a portal across the gap on the ceiling, and put another one near you. Go ahead and crouch into the side room once you get over there. You’ll find a lot of miscellaneous objects, including a radio after the first play through, although not a whole lot to read this time.
[[File:Portal_Chamber_18_ceiling_placement.png|thumb|left|This portal location should place you confidently on the next ledge.]]
Continuing on, there is again a nice portalable ceiling, but no way to simply walk into a portal. You can, however create one on the next platform’s wall, and get a running jump into it (put the portal a little low, as even if you jump too high, you can still get into a portal below you... unless you’re carrying the radio). The platform you’re aiming to land on does not cover as large of an area, so be sure to adjust your fall accordingly. Also take note that you might fly through [[Portal/Tips and advanced techniques#Angle flinging|at an angle]], making it tougher to accurately land where you expected. This can be prevented by actually landing on the bottom of the wall portal before coming the whole way through.
[[File:Portal_Chamber_18_first_fling.png|thumb|left|Drop into here and you'll have the necessary momentum to get to the button.]]
Another ceiling portal, and you’re off to platform 3, followed by wall placement to get you onto platform 4. Unfortunately, the door is closed, and tracing the wire leads to yet another platform. Some familiar sights are here, letting you know how you should get to it; there’s the extended panel showing your top portal placement, and a checkered floor on a level below you showing your bottom portal placement. Fling away!

Now you’ve got a big button... but nothing to put on it. And so we have to make our way into the next area we can go into. You get a lovely preview of what you’re about to run into through the glass.

=== Part 2 - Turrets and Energy Pellets ===
{{Achievement|name=[[Portal/Transmission_Received|Transmission Received]]|image=Portal achievement Transmission Received.jpg|width=350px|description=The second radio is a mystery at first, because you can hear it, but can’t seem to see it. It is on top of the pellet receiving container. Place one portal on the floor in front of the container, and another on the low checkered floor to the right of the entrance. [[Portal/Tips and advanced techniques#Post-fling maneuvering|An adjustment once you fly through]], and you’ve got it. Bring it to the back of the area with a small button (below the cube dispenser area).|progress=21|total=26}}
[[File:Portal_Chamber_18_turret_room.png|thumb|left|Water and pellets and turrets (oh my!).]]
If you can manage to look through the glass and not get your view obstructed by turret fire, you’ll notice two laser beams indicating turrets facing away from the entrance, and two turrets facing to your right. Because of that, when you press the small button and open the entrance, go through on the left side by crouching under the support bar first to avoid any bullets.

Now that you’re safely in the room, let’s get rid of the real troublemakers in this situation. Unfortunately, you can’t reach most of them yourself, but there is something you can redirect at the turrets: the pellets! Very conveniently, the laser beam shows you exactly where the turret is looking straight ahead at, so simply take some time to place portals on a burn mark and a laser beam end (be careful, they can fire through portals if they see you!), and watch them fall into the watery abyss.

[[File:Portal_Chamber_18_pellet_redirection.png|thumb|left|Bombs away!]]
[[File:Portal_Chamber_18_button_access.png|thumb|right|You could use the extended platform, but here is safer.]]
Now there’s still an active pellet launcher, and the receiver (inside the container on the left) will power a moving platform. You can redirect a pellet, placing your portals using a burn mark and the extended panel off to the left (the far one, not next to the small button). As soon as the pellet passes through the portal, recreate portals so that you can reach the small button to open the door to the receiver. You must press the button in this short span, as the door opens only very briefly.
{{-}}
[[File:Portal_Chamber_18_return_portals.png|thumb|left|First create portals that you will return through.]]
[[File:Portal_Chamber_18_fling_portals.png|thumb|right|Then create these as you go, to fling yourself to the cube.]]
You can now take the moving platform over. You cannot jump to the cube, but you can jump to the lower area. Pressing this button, you will notice the entrance panel once again opens up, staying at an angle for a period of time before closing. Assessing the situation, the angle will be excellent for a long fling, and the checkered low floor on the water level creates the necessary momentum. Unfortunately, you have to get over there first, and so you must create portals to get back, press the button, go through, place a portal on the angled platform as soon as it stops moving, and fall, placing a portal below you. This will easily throw you to the cube. Finally!

But wait... now we have to get out of here with this cube. Go ahead and take the cube over to the entrance, but then go yourself back down to the small button. Portal placement, a push of the button, through the portals, grab the cube, and crawl back out of this terrible room. Cube on the button, portal back to platform 4, and through the door!

=== Part 3 - Linked Flings ===
{{Achievement|name=[[Portal/Transmission_Received|Transmission Received]]|image=Portal achievement Transmission Received.jpg|width=350px|description=The third radio is at the bottom of the huge pit that starts your fling in the final room. Bring it up to the entranceway, but you won’t be able to take it with you over the platforms. Once you’ve reached the very top, you can shoot a portal on that exit platform, and another on the wall at the very bottom. Grab the radio, go back through, and the signal’s in the middle of the exit platform.|progress=22|total=26}}
[[File:Portal_Chamber_18_final_room.png|thumb|left|The tall room with just a few platforms.]]
Yes, that’s right, you’re not done yet. This part is all about redirecting one single fling with many portals.

[[File:Portal_Chamber_18_room_climb.png|thumb|left|The next portal will be a blue one on the platform just sneaking into the top of the picture.]]
Now on your left, you see the floor on the bottom. Put a portal there and another on the platform you see straight ahead. Now once you jump, you may see the floor of the higher platform. What you want to do is shoot the color portal necessary so that you will now fly up through the next platform. It’s all back and forth as far as what color portals you will be placing. If you do mess up (but are still living), place a portal on the wall at the entrance so you can start over. If you happen to be on (or have a portal on) the platform with 3 dots, you can simply shoot one portal on the angled platform, another on the platform with 1 dot, and you can jump into that portal to get to the end.
The last platform is slanted, which will fling you to the exit. Proceed to the elevator as GlaDoS talks to you.

{{-}}
== Advanced ==
Numerous changes have been made to make the advanced chamber more difficult. At the beginning, the ceiling is no longer portalable. Instead, place an orange portal as high up as possible on the wall. Create a blue portal on a wall you can walk to, and step into it. Make sure you don’t fall into the water, and instead shoot a blue portal on the ground so that you fling across the water.

If you’ve done that already, you probably notice that there is now seemingly no way to get up to the next level. What you must do is while you are flying over, shoot a portal of either color onto the floor of the next level. If you miss, just shoot a portal back to the beginning and jump through to try again. Once you succeed, place the other color portal on the wall and jump through.

Now you should be on platform 2. Again, no ceiling to get to platform 3. If you look below platform 3, there is a block on the right wall that seems pushed out enough to stand on. Create a portal just next to this, and come through slowly so you don’t go swimming. From here you can see the low platform in between 3 and 4, and a nice wall above it, so portal up to it. Walk to the edge of this platform and you can see a wall above platform 4 to portal to. Now go ahead and place a portal to fling over to the button as normal.

The next room has no pellets, which makes getting rid of the turrets a lot tougher. On the other hand, two of the walls have portalable surfaces much higher, making it possible to reach the turret platforms yourself. The low fling platform has also been moved to below the cube and button areas.

Get to a slightly higher ground, such as on top of the extended platform near the pellet receiver. Place a portal in line with the first turret (closest to the entrance), at about the right height so that you can fling into the turret and end up safely on its platform. Quickly move if necessary to the edge of the platform to avoid the second turret’s fire. The game will auto-save once you have done so (after each turret), so you will not have to repeat them all. Place a portal to get ready to fling to the second turret (the one currently closest to you), and another one on the ground of the main platform. Jump through and fling into the second. The third turret will see you, so quickly jump towards the wall you just flung from, shooting another portal low on the wall, and come on through to the main platform. The third turret you can easily jump to from a portal on the wall, and similarly for the fourth.

Now you can safely proceed as normal to the button. A different method must be used to fling to the cube this time. One way is to press the button, shoot a portal on the angled platform after it stops, and then another on the low floor below you. The first fling will only get you far enough to reach the floor again, but place the same color portal again so that you can [[Portal/Tips and advanced techniques#Multi flinging|double-fling]] over to the cube.

Alternately, prepare by shooting a portal at a high wall near the pellet receiver, and another at one of your accessible walls. Press the button, look through the portal, and wait for the platform to finish moving. Go through, shoot one portal on this platform, [[Portal/Tips and advanced techniques#Changing both portals mid-flight|and another]] below you before you hit, and you will fling to the cube.

Either way, take the cube back toward the entrance, go back to the button, press, portal, and through you go. Cube on the button, and on to the last test.

Another option is to skip killing the turrets entirely using a method similar to least portals gold number 8 below. When you enter the turret room(crouching round the left to avoid turret line of sight), wait until the entry/exit wall is fully open and diagonal, place a portal on it, and quickly go round the other side and back past the large button in the previous room and drop to the lower of the two low platforms, placing another portal so you fling yourself across the turret room. Quickly pick up the cube and use it as a shield if need be, back up to the center wall and wait for the turrets to go passive. Carefully walk off the edge and press backwards(default s on pc) to land on the platform with the small button which will open the way back to the previous room. Use cube as shield as needed. Set it down behind a corner and place one portal to either side of this small alcove and one either above or next to the moving wall panel(aka entry/exit for this room) on the opposite side of the room. Hit the button and carry the cube through your portals and out of the room. You may want to observe a slight pause so that you arrive on the other side of the portal as the exit is fully open so you can go walk and not crouch through as fast as possible to avoid turret fire. Place cube on the big button and head off to the last room.

The last room is similar to the original, except that as soon as you reach the next higher platform, the lower one will drop into the water. What this means is that you must place the next portal on the first try for every jump except the original. Make sure you look down into the portal each time you go into one, as when you come out the other side, you will simply have to move your view down, rather than the confusing automatic re-orienting that would occur if you were facing front. If you mess up, you must portal back to the beginning and potentially start over, however you can actually start from the platform you just came from if you place the right color portal.

== Challenges ==
=== Portals ===
;Bronze at 30 portals
# Blue portal on the ceiling above the far area.
# Orange portal anywhere accessible. Fall through.
# Blue portal on the ceiling above the two-dot platform.
# Orange portal on the wall that you can jump into.
# Blue portal on the ceiling above the three-dot platform.
# Orange portal on the floor below you.
# Blue portal on the extended panels above the four-dot platform.
# Orange portal on the floor below you. Stand on the four-dot platform.
# Orange portal on the lower floor in between you and the button. Jump into it and fling over to the big button. Continue and press the small button to enter the turret room.
# Blue portal on any of the four scorch marks.
# (11-14) Orange portals on the spots that each turret’s laser is at on the wall. Wait for the pellet to travel through so it can hit the turret before shooting your next orange portal.
<ol start="15">
<li> Orange portal on the left far extended panel (facing the receiver). Wait for the pellet to pass through.
<li> Blue portal near the small button on your left.
<li> Orange portal near you (not on the entrance panel). Quickly go through and press the button to let the pellet in. Now ride the lift over to the other small button.
<li> Blue portal on either side of the small area you are currently in. Press the button and quickly walk through the portal.
<li> Orange portal on the angled platform as soon as it stops moving.
<li> Blue portal on the floor just above the water. Fall into it quickly and fling over to the cube. Grab it and ride the lift back to the main area. Drop the cube off and ride back again to the tiny area with a small button.
<li> Blue portal on either side of the small area.
<li> Orange portal on a wall near the entrance/exit (not the platform that moves). Press the small button, go through the portal, grab the cube, and exit. Place the cube on the big red button.
<li> Blue portal anywhere on or above the four-dot platform. Jump down to the lower platform.
<li> Orange portal anywhere accessible. Walk through, and continue to the last room.
<li> Blue portal on the first platform.
<li> Orange portal at the bottom of the large drop. Start your fling as normal.
<li> Orange portal on the one-dot platform.
<li> Blue portal on the two-dot platform.
<li> Orange portal on the three-dot platform.
<li> Blue portal on the angled platform.</ol>

;Silver at 25 portals

 Many shortcuts are possible, but here’s a set that hits 25 exactly.
# Blue portal on the ceiling above the far area.
# Orange portal anywhere accessible. Fall through, being ready to place the next portal.
# Blue portal, as you fall, on the floor of the two-dot platform.
# Orange portal on the wall that you can jump into. Go through.
# Orange portal on the ceiling above your current platform (two-dot), directly above your floor portal. Look into the floor portal to prepare for the next portal, then enter.
# Orange portal, as you fall, on the far left corner (or close to it) of the floor of the three-dot platform. Flying back into the blue portal, you will fly up through this new portal and be able to [[Portal/Tips and advanced techniques#Post-fling maneuvering|maneuver onto the platform]] with the big button. Continue and press the small button to enter the turret room.
# Blue portal on the scorch mark located on the wall you just entered from. Aim a little low and to the right, but make sure the pellet will still enter this.
# (8-10) Orange portals on the spots that each turret’s laser is at on the wall. Wait for the pellet to travel through so it can hit the turret before shooting your next orange portal. This time, don’t worry about the turret farthest from you.
<ol start="11">
<li> Orange portal on the left far extended panel (facing the receiver). Wait for the pellet to pass through.
<li> Orange portal near the small button on your left. Run and jump, holding towards the blue portal, and you can travel through it. Press the button when you come across to the other side to let the pellet in. Ride the platform to the tiny area with the other small button. Since there’s still a turret, you may want to jump early to avoid fire.
<li> Blue portal on either side of the small area you are currently in. Press the button, and wait for the angled platform to stop moving.
<li> Orange portal on the angled platform as soon as you can. Quickly come on through.
<li> Blue portal on the floor just above the water. Fall into it quickly and fling over to the cube. Grab it and use it as a shield between you and the turret as you jump to the lift and ride it back to the main area. Drop the cube off and ride back again to the tiny area with a small button.</ol>

 Portals 16-25 are the same as portals 21-30 in the bronze description.  

;Gold at 16 portals

Again, various shortcuts give you different amounts, but this is probably the easiest way to get down to 16.  Portals 1-6 are the same as in the silver method. Stop before entering the turret room.
<ol start="7">
<li> Blue portal in the middle of the low platform between you and the four-dot platform. Now move to the entrance to the turret room. Prepare for the next fast move by crouching under the metal support, within small-button-pressing distance. Do so, and walk towards the left side of the panel, moving into the room as soon as possible. Quickly walk around to the front of the angled panel.
<li> Orange portal on the angled panel as soon as it has stopped moving. Very quickly continue all the way around the panel, exiting the room again from the opposite side of the panel (in order to skip the slow crouching). Run past the small and big buttons, falling into your existing blue portal. If you have done this fast enough, you will be flinging towards the cube. All 4 turrets are still active, but if you are all the way in the back and centered left and right in the cube area, none will be able to see you. Grab the cube, crouch, and use it as a shield against the two left turrets (stay a little to the right to avoid the right two turrets) as you inch closer to the edge. There is a room directly below where you're standing. This part can be tricky. You'll need to walk off the ledge while holding the cube, and then immediately move backwards (and possibly sideways) so that you land on the ledge of the room below you. Move back to avoid additional turret fire.
<li> Orange portal on a wall on either side of you. Take the cube with you through this portal. Take note that you will be jumping into a wall portal and coming out through a floor portal, so you should be sure to move sideways or you may fall back in. Now with your back towards the near wall, move left and look up and right.
<li> Orange portal on the extended panels above what is the four-dot platform. Walk with the cube through it and onto the four-dot platform. Now you need to fling both yourself and the cube back to the button. You may want to [[Portal/Tips and advanced techniques#Flinging an object|drop the cube in the portal]] first, but it is possible to [[Portal/Tips and advanced techniques#Flinging with an object|fling while holding the cube]]. Place the cube on the button. Walk to the ledge and jump to the lower area that has the floor portal but do not jump through the portal. Instead, simply walk into the portal once you have landed. You should now be on the four-dot platform. The door is now open and you can walk through it to the final room.</ol>

Portals 11-16 are the same as portals 25-30 in the bronze description.

Additional reductions can also be made to this room to achieve sub-16 counts.
* Multiple methods can get you to the point of entering the turret room after using only 6 portals, reducing the count by one.
* This method gets you there with only 5, reducing the gold method by two. Move as far towards the drop and to the left towards the wall as possible. If you crouch and look to the right of the normal ceiling, you will be able to see a tiny part of the next higher ceiling. Shoot a blue portal there, and an orange one anywhere reachable. Be sure to maneuver yourself when you go through so that you land safely on the two-dot platform. Now face the three dot platform and move back and right as much as possible. Place an orange portal on the floor just in front of you. Hop to the other side of this. Look into the portal while crouching right next to it and spot the three-dot platform. You will want to place the next portal on the far left corner of this platform. Get ready, and walk through. As soon as you do, shoot a blue portal there, and hold left. Look down to aim into the orange portal, and fling up, [[Portal/Tips and advanced techniques#Post-fling maneuvering|maneuvering]] to the button platform. You can now continue at portal 7 in the gold method, which will really be portal 5.
* In the last room, place the portal on the two dot platform as far left as possible. When flinging up from this, it is very difficult, but possible, to place a portal on the angled platform directly from here, reducing the count by one. When facing the angled platform, hold right as you come up, shoot the portal when you can, and then hold left and look down to hopefully fall back in.

=== Steps ===
Once you get to the small button to enter the turret room, activate the button, quickly shoot a portal on the angled platform when it stops, and fall to the low floor in the room to fling to the cube. Alternately, use the method described in the least portals gold method to fling to the cube. They both have their own advantages, and thus often end up about the same number of steps. Try both, and see which works better for you.
;Bronze at 150 steps
;Silver at 120 steps
;Gold at 85 steps

=== Time ===
;Bronze at 2 minutes, 10 seconds (130 seconds)
This medal can be obtained by doing all of the steps in the regular method. Make sure you don’t miss any pellets, and make sure you get portals onto the next higher platform on your first try every time in the last room.
;Silver at 2 minutes (120 seconds)
If you reach the turret room quickly enough, you can start the turret-killing process one pellet sooner, which sets you up to be able to complete the chamber in under 2 minutes.
;Gold at 1 minute, 13 seconds (73 seconds)
For this medal, you will have to skip the whole pellet process. When you enter the room, put a portal on the angled platform, and fall to the low floor, placing a portal to fling yourself to the cube. Quickly grab it, block some bullets, and move to the lower room, placing portals and pressing the button to come back through. From here it is normal.

== No Cheating [[Portal/Speedrunning|SpeedRun]] in One Segment for Mere Mortals ==
This is probably the most exasperating chamber for speedrunners.  A tricky, but learnable, finesse will get you through Part 1 feeling good about yourself.  Part 3 just has to be executed perfectly according to the normal walkthrough, but is also rewarding to the player.  But in between ... there's Part 2.  Following the normal walkthrough is easy, but tedious and time consuming.  The clock is ticking but you're standing there, waiting for the pellet or the moving platform, and all your skill and effort in the previous chambers is wasting away.  The only way to get a better time is to follow the method used for a gold medal time challenge.  However, there are several points here where you stare death in the face.  If you are shot to death or fall into the toxic goo, that's going to be about twenty minutes of effort down the drain.  You can quicksave and load and try again if you die, but this erodes the advantage of the fast method.

'''Part 1 - Drops and Flings''' : If the normal walkthrough is executed promptly and perfectly, you will take about thirty seconds to get from the entry chamberlock to the button outside the turret room.  A second or so can be shaved off by portaling along the hallway instead of walking.  Using the method described here, you can cut that time down to twenty seconds or even less and impress your noob friends with your ninja skills.

Step out of the chamberlock and immediately shoot the orange portal at the most distant section of portalable wall that you can see, which will be on the left side of the room and ''below'' the level at which you are standing.  Turn to the wall and place the blue portal there.  Now, use [[Portal/Tips and advanced techniques#Peek-a-portal|peek-a-portal]] to move the orange portal to the ceiling over the ''second'' platform (that is hidden around the right hand corner).  The exact placement is important and you will have to practice it until the next move works out properly.  The portal has to travel a long way, so you will have plenty of time to pull back.  Don't go through.  Instead, move the blue portal to the floor.  Then walk around the blue portal until by looking through it you can see the platform with the three-dot symbol on it.  Crouch, aim the portal gun slightly high to hit the platform well to the left of the symbol and drop through the blue portal.  As soon as you're through, fire the orange portal, then immediately look down and place the blue portal underneath you (on the platform with the two-dot symbol).  When you come up, turn slighly to the right and you will see the door to Part 3.  In mid-air, move the orange portal to the middle of the protruding section of wall above the door and look down to place the blue portal underneath you.  This fling will take you right over the button and into the tiny room beyond to start Part 2.

'''Part 2 - Turrets and Energy Pellets''' : As in the normal walkthrough, press the pedestal button and crouch under the piston that operates the door to the turret room so that you can enter without being immediately shot at.  At this point, there are two ways to get over to the other side of the room where the cube is.  You can either start the moving platform and ride that or you can fling over immediately, using the angled door panel, before it starts to close.  To ride the moving platform, you first have to eliminate all the turrets or you will be shot to death.  That can all take three minutes.  Obviously, for a good speedrun time, you'll need to fling.  So, as soon as you get out from under the piston, walk around the door as it tilts up and head for the right-hand edge of the entry shelf, where there is a flat area down below from which you can start the fling.  As you go, turn to the right (so you'll have to be walking to your left) and watch the door panel.  As soon as it stops tilting, place a portal on it.  At about this time, you will begin to take damage from turret fire.  Grit your teeth, turn back towards the cliff edge and press on.  You need to get over that edge before you die.  This may take practice.  Place the other portal as you fall and you'll fling safely across the room to the alcove where the cube it.

What you have to do now is bring the cube to the front edge of the alcove, carefully drop off and move backwards in mid-air so that you don't fall into the toxic goo but instead land in the pedestal button alcove below.  Oh, and you'll be under turret fire again.  Once again, practice is key.  Figure out which turrets are shooting at you and hold the cube up for protection.  Unfortunately, this makes it harder to see where the edge of the alcove floor is.  If you just go off the edge at a full walking pace, you're likely to end up in the goo.  The turret fire may, if you're lucky, push you back and help you land in the alcove below.  If this isn't working for you, no matter how hard you try, it may be possible to selectively take out the dangerous turrets with the energy pellet from where you now stand.  Then you can concentrate on gently dropping off the edge and getting into the pedestal button alcove.  Don't forget the cube.

The danger is now over, so just move quickly through the remaining steps to get out of the room with the cube.  Put the cube down near the middle of the alcove.  Go to the alcove opening and press the pedestal button.  The door will begin to open.  Put a portal on the wall above and slightly to the left of the panel's center.  When you drop out of that portal, you want to be hidden from the turrets by the door panel and have a clear path to walk out of the room.  Turn, and put the other portal in one of the alcove walls, either to the right or to the left, above the step.  Pick up the cube and go through the portals.  Leave the room and put the cube on the button to open the door to Part 3.  Portal yourself over to the door, dropping to the platform below to find a portalable surface, and go through.  From passing over the button at the end of Part 1 to getting through the door to Part 3 should take about 41 seconds; a big improvement on three minutes.

'''Part 3 - Linked Flings''' : Once you are through the button-controlled door, follow the normal walkthrough, above, but practice and use a better sequence of portal placement.  As soon as you can, put a portal on the first platform over the toxic goo.  ''Then'', hurl yourself into the pit and place the other portal at the bottom so that you go through it.  Putting the portal in the pit first, looking up to put the other one on the platform and then dropping into the pit will just waste time.  As you fly up from each platform in turn, you need to know which way to look to place a portal on the next higher platform.  Practice, and always do exactly the same thing so that you always get the portal placed on the first try.  Instead of alternating portal colors, which can go wrong if you are distracted, consider always putting one color ahead on the next platform and the other color on the platform you flung up from and are now plummeting back towards.  There is plenty of time to do this.  Every time you fly up, turn to locate the next platform, shoot blue onto it (for example), then look straight down and shoot orange.  This may let you concentrate better on the turn you will need to locate the next platform.  A respectable time from getting through the button-controlled door to reaching the exit chamberlock is twenty five seconds.  The whole chamber should take about one minute and twenty five seconds.

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