I’ve made the ShrimpKey - a MakeyMakey-substitute.
It can be made for less than 10 USD.
The ShrimpKey is a shield for the Shrimp (shrimping.it) - an Arduino Uno-substitute.
But it should also work with an Arduino Uno (although I haven’t tested it).
More information and full building instructions can be found on my blog: http://fromScratchEd.nl
Please let me know if you’re going to make one!
Twitter: @fromScratchEd #ShrimpKey