Clockwork Robot has introduced a solar powered theremin kit:

This is an electronics kit suitable for beginners but it DOES require some soldering.

With very few parts you can build a tiny solar powered theremin enclosed in an ALTOIDS mint tin. So when the oil runs out, the ice caps melt and civilization crumbles to dust, thanks to the Heliophone, we will still have electronic music

The kit contains all the parts required to make the solar powered theremin including a solar panel, a custom made PCB and full color instructions.

The device functions best on bright sunny cloudless days. By flipping open the lid and letting the light hit the solar panel the theremin will generate a high musical note. In order to play a tune you can either cast a shadow over the panel with your hand (this allows you to play with an action very similar to the original theremin) or you can tilt and angle the theremin in relation to the sun to vary the note.

With practice you can pick out notes very precisely and in optimal weather the device will generate tones over several octaves, so it is possible to play real music on the thing.

This looks like a fun way to get your green on….

The kit is £9.95, including international postage.