HackaDay has a nice tutorial that looks at hacking the Thingamakit anthropomorphic synthesizer.
Hacks include adding a waveshaper knob, a sine wave switch and an audio input. If you’re thinking about getting a Thingamakit - this is a must read before you dive in. Kits are $55, or $65 with the enclosure.

Surachai’s video capturing the creating of a ThingamaKIT synth monster.

This video showcases the Thingamakit, a fun DIY project that lets you build your own anthropomorphic noise maker.
Comes with:

detailed instructions
fully labeled components
simply layed out circuit board with minimal hand wiring.
2 ready to blink LEDacles
control panel and face stickers

Bleep Labs has introduced the Thingamakit - a DIY project that lets you build your own anthropomorphic noise maker.
According to Bleep Labs, the Thingamakit features “all the sounds of Thingamagoop plus
triangle wave LEDacle with shape and speed control. Second photocell patchable to modulator and photocell rate. Square and Triangle wave output.
The satisfaction for making an [...]