The sample recycling operator came across the occasional one that had polymerized, over months of identical ambient storage to the other bottles in the case which could still be handled as liquids.
Broke it out of the bottle and brought it into the office, where it was completely odorless and sitting there like a promotional acrylic paperweight with nothing embedded inside to promote :)
If this tank has a giant disk of clear acrylic at the bottom, it "might" be unprecedented to remove it intact and turn it into a fairly sizable lens if possible. If not clear, maybe even a mirror of some kind anyway.
Although there is probably some internal piping from inside the tank, embedded for display purposes primarily at this point ;)
Often if one wants to make something "larger", dropping superglue, adding bicarb with a silt, blowing away and dropping another layer works fairly well (it's a bit of a brittle but still quite hard mass that is created quickly).
Then at some point I realized that I overdid it!
Easy-peasy, a file and sandpaper to the rescue, I thought.
Aand.. I spent x3 more time shaving off the excess than building it! It's super tough.
Also, your breath might help in a pinch (it's humid).
For comparison, there is a nice video by NileRed https://www.youtube.com/watch?v=phNLecfyWS8 He is making Bakelite that is a type of plastic. It's a tiny amount, in a lab, on purpose and he may make a few attempts. Anyway it overheat and instead of a nice piece of plastic he got a nasty block of foam with burned plastic. No imagine a huge tank of a similar chemistry reaction.
It's amazing stuff.