From StrategyWiki, the video game walkthrough and strategy guide wiki
- Bronze: 8
- Silver: 6
- Gold: 4
4 Portal Strategy
- Using the same trick from the last challenge, stand directly under the cube dispenser after having pressed the destruct button, grab the first cube that falls and shake it in and out of the cube dispenser until you have spawned three cubes. (Rapidly pressing the duck button is the easiest way to do this.)
- Shoot a blue portal through the hole into the area with a button.
- Shoot an orange portal on any wall nearby then place a cube on the button.
- Shoot a blue portal on the upper wall to your left and place another cube on the button there.
- Bringing the last cube through the portal with you, shoot an orange portal on the opposite wall and place the final cube on the button.
- Drop down and proceed to the exit.