Player 1: This is a nice and simple challenge before the final co-op chamber. As soon as you enter the room, look to your left for a little rectangular area, which has a shoot-able ceiling and walls (but not a shoot-able floor). Place a portal on the ceiling section, go to the propulsion gel dispenser, set a portal here and use the button to release the gel. You’ll want to reposition the portal halfway through so it coats the whole of the floor. Player 2: Once there’s enough gel on the floor, create an ‘infinite loop’ portal and keep running!
Player 1: Place a portal on the angled wall panel located up and to your right and then run down to the end of the chamber with the two red switches. Press the one straight ahead of you and - quickly - run back a bit. Now shoot a portal at the right-hand wall of player 2’s loop and they’ll be ejected at high speed onto the platform you’ve dropped by pressing that button earlier.
Player 2: Run to the end and ask player 1 to quickly press the other red button to release the crate from the dispenser above you. Catch the cube and then run back as fast as you can (as the platforms are on a short 15 second timer)! Once you’re safely on the ground, simply drop the crate into the switch cradle to open the exit to the final chamber.