Even in Kyoto

I think to regenerate it you have to calcine it, which is in the red-hot range.
I've seen people do something similar using a garbage bag to line the system, to prevent escape. I'm also told that any sort of shop machinery, like a tablesaw or bandsaw, will do a pretty good job of debubblizing the plaster.

The other day I found a blog about a guy rebuilding a 1915 motorcycle. he casually mentioned that he'd rebuilt a bicycle pump as a vacuum source, able to crank down to 1/100 of an atmosphere with assiduous application of the pump. I haven't yet found details, but that would certainly debubblize plaster effectively.