Although Oskitone’s Scout isn’t the world’s most flexible synthesizer, you can’t dispute its attractiveness.
There are no frills on this Arduino-compatible monophonic beauty, which can also be ordered completely constructed ($125), but half of the pleasure is putting it together yourself.
When you include in the extense of 3D printing your parts, the Scout may be had for as little as $42.
It has a 17-note keyboard, a volume knob and an on/off button. Hands-on tinkering isn’t an option although it can be hacked if you’re interested in that kind of thing.