Step 1: Get Your Theremin Ready
I made my theremin from a kit i bought from Harrison Instruments for around $45. http://harrisoninstruments.com/
I wont go into detail on how to build it, as the theremin itself comes with excellent instruction.
Step 2: Find a Tea Tin and Drill Some Holes
There are 4 holes needed to be drilled. Make sure when drilling that you aren't opening the holes up too wide, or else your components will slip right through them.
1) potentiometer knob
2) power switch
4) 1/4" audio out jack
5 optional) there is a small audio taper pot used for tuning that's very small and is actually located an the circuit board itself. Unless you fine tune it BEFORE you put it in the tin, you will have a really hard time getting to that pot once all the parts are screwed in (which was my big mistake). My suggestion is either loosely place everything in its spot, and then take out the circuit board and tune it, or drill a small hole where ever your tuning pot is. It needs to be just big enough for a small flat head screw driver to fit into.
Step 3: Install Your Components
I put my audio out jack on the lower right side, as it seemed the most logical.
Step 4: The Antenna
I however simply used a small antenna I lifted from an old remote control car remote. I was initially having trouble thinking of a good way to mount the antenna. I had to keep it connected to the circuit board ONLY and not let it become grounded (which kills the signal instantly) by touching the metal tea tin. Eventually my friend suggested I use an RCA jack!
I soldered the antenna to the male end of an RCA jack, and wrapped the bottom with some white electrical tape. This kept the metal of the antenna from touching the grounded casing around the male end of the jack. Then I soldered the female end to the circuit board and screwed it to the lid of my tea tin.
This was a very nice outcome, as it allowed for the antenna to be removable.
THAT'S IT YOU'RE DONE!