I don't mind admitting this had me completely flummoxed for a good while. Once you manage to access the conversion gel it becomes a bit of an easy ride, but that's quite a relief to be honest.

I strongly suggest adding a light strip under the window to block the portal-bumping exploit! Normally I don't regard this as crucial, but the difficulty level here is sufficient that you're in danger of players assuming that you've made some lame glitch map, or just solving it that way out of sheer spite. (I know I had to resist the temptation.)