Nevermind
I will post a much improved version soon, I won't bother with this.
"Remember, the platform was sliding into the fire pit and I said, 'Goodbye', and you were like 'No way!', and I was all, 'We pretended we were going to murder you'. That was great!"
As always, first releases need a bit of work. However, yours doesn't need much. I just think that if it weren't for the fact that goo doesn't kill you instantly in this version, I'm pretty sure the last chamber can't be done. At least, I couldn't find a way to do it.
My reccomendation would be to add some way of accelerating yourself out of the
Looking forward to future releases 
i must be missing something really obvious but i get into the door and use the cube to get to the first platform and then i have no where to go...
I guarantee you it is possible and no glitching is involved. You have to look around and find all your resources. I don't want to give too much away just yet. I'll add a couple hints scratched in blood.
Meanwhile, can you tell me if there are missing textures via noclip?
"Remember, the platform was sliding into the fire pit and I said, 'Goodbye', and you were like 'No way!', and I was all, 'We pretended we were going to murder you'. That was great!"
Done it. I don't know if that was the solution but about the 45? jump,
Author of Minecraft mods (MAtmos, Minaptics, NoteSlider) and Garry's Mod addons (Gunstrumental, SharpeYe, GarryWare, DepthHUD).
That isn't the simplest answer, the intended solution doesn't require flinging. Good find though.
Can someone put this in [WIP] section?
"Remember, the platform was sliding into the fire pit and I said, 'Goodbye', and you were like 'No way!', and I was all, 'We pretended we were going to murder you'. That was great!"