i think you can do this, assembly of 4 parts of fiberboard, so you can mount and unmount the thing.
make it double wall with 703 2" in the middle.
Chop a suare and put a plate of acrilic material, but make sure it is not parallel positioned. so you have a structure to use when u need a booth, and when you don't just split the parts and put them elsewhere.
Sorry bout my english i hope u can understand the idea, i did it and it works very god, assuming your studio is isolated and acustically treated correctly.
Bye
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yes i'm Just plain stupid!