Yudo makes iOS apps, and has quite a few musical ones in the App Store. The company's Kami-Oto is an actual MIDI controller made of cardboard so you can use it with pretty much any software on computer or mobile device. There's a main circuit board, silicon contact pieces, and cardboard black and white keys you punch out and assemble atop the rest. The company estimates it will take about 30 minutes to make. There are two models, one that uses micro-USB and one that uses Bluetooth. The Kami-Oto also has its own integrated sound generator and tiny speaker, as well, for self-contained music-making without an app.

You can pledge ¥5,000 (about $45) for a Kami-Oto with the Bluetooth chip and extra cardboard sheets on Kickstarter right now. A non-Bluetooth version without extra keyboard parts is offered for pledge sof ¥3,000 (or $27), too. Delivery of all models is expected in August of this year.