It's actually a green force-field cushion. So turn it on from the button down the dead-end hall way. Then go back to start, through door on right, down the hallway, to the elevator. Go up to the walk way, and jump off. Be sure to land on the green force field cushion.
Level 4 is also confusing: walk up the stairs, hit button to start arm swing. Jump through ejector force field at right time so you get hit by middle of swinging arm. (Too early or too late, you will get to no-way out sections, have to jump off and die to restart level.) It will push you to middle section of other side, then you can find walkway to stairs down to room with holosolid model.
Thanks for feedback -- this my first game ever, and I'm beginning to appreciate how difficult to design game play, but somehow add clues or signs so players can figure out what they are supposed to do. Yes, I need more practice -- and alpha testers :) :P