i got out by portaling myself to the bridge thing before it opens and then just walked to the exit. i couldnt get the cube to drop either

Didn't see how to spawn the cube where the gel goes and so never used the gel either. Very interesting.

I "solved" tjis map by simply portaling myslef next to the exit (which was open), jumping onto the edge of the inactive lightbridge, and then jumping straight to the exit.