Fire a portal beneath the Propulsion Gel tube, and another on the wall opposite the ramp. Press ... 2 Batman Arkham Knight Riddler guide to solve every challenge The final step is to reach the ...

As the player explores the depths of Aperture Science in the midsection of Portal 2, they’ll encounter ... With the portals open, press the button to cover the floor in gel.

When you're there, fire a portal onto the surface on the wall opposite the exit door so that you and the cube fall into it. Let the cube press up against the button, and drop to the exit.