When you first enter the room, Wheatley will open up an exit for you. Be sure to take a close look at that exit, because you'll see something interesting up there.
Now put a portal on the ceiling that the inactive light funnel is pointing at. Then put a portal on the wall across from the platform under the cube chute. Put it as low on that wall as you can. Press the small red button to make a cube fall onto the platform below the cube chute. Then go stand on the big red button to activate the light funnel. If you put the portals in the correct places, the funnel will push the frankencube off of the platform and onto the wall.
Now put a portal on the wall below where the light funnel is shining. The cube will fall into the funnel and come over to you. Get off of the big red button.
Go over to the glass wall that has a second big red button behind it. Use your portal gun through the round hole in the glass wall to create a portal in there. Then create a portal of the other color on a wall that you can walk through. Take the frankencube through the portals and put it on the big red button. This activates the dripping orange gel.
Put a turret on the ceiling above the light funnel, then put a portal of the other color on the wall between the light funnel and the glass wall area where you put the frankencube. Step on the big red button to activate the light funnel. The orange gel will be carried in the funnel. When the gel is over the ramp on the right, move a portal so the funnel disappears, making the gel fall. You want to coat the floor and the ramp with the gel.
Use portals to retrieve the frankencube from the glass-walled area. Put it on the big red button that activates the funnel. Now walk behind the big ramp and put a portal on the wall to the right of the big emancipation grill in the distance. Put a portal of the other color where the funnel is shining. This will make the funnel shine toward the exit.
Now run along the orange gel. You should end up in the funnel, which will take you to the exit. Go through.