I finished building a PAIA Theremax kit tonight. Well, almost, it has some issues. Hopefully tech support will get back to me tomorrow.
Anyway it does make sound, and sounds pretty cool. I didn't get the wooden box they sell, becuase I planned on making my own. I got impatient though, and decided just to temporarily install it in the cardboard box they shipped it in.
It's actually pretty simple to build, just time consuming. There are a LOT of resistors, capacitors, transistors, etc to be soldered onto a little teeny circuit board.
The issue I'm having with it is that when you try to use the volume antenna it makes a whistling sound, in addition to the pitch you're supposed to be hearing. According to the PAIA Theremax FAQ, this was a problem with earlier kits that has since been resolved so I'm wondering if the fix was inadvertantly left out of my kit. Or if I screwed something up maybe they can point me in the right direction.
Anyway it was fun to build, only took about 3 nights worth of work and hopefully when I get it up and running will be fun to mess around with. Then I need to get it into a respectable cabinet!