I felt like the Open Theremin is a little too exposed and I was afraid it's going to get broken. I decided to made it a case. I made it from scratch out of Red Mahogany from Rockler Woodworking:
You can see here how the board is screwed to the back of the faceplate with small wood screws and standoffs, and then the faceplate attaches to the rest of the case with magnets:
I don't have a pic, but I inserted a 1/4" tee nut in the back of the case so it can be screwed onto a standard camera tripod.
The only finish on the wood is a good heavy coat of Tung Oil. I thought it came out quite nice.