Oddly Specific Objects founder Joey Castillo has designed a couple of interesting open hardware projects over the years. Those include the Sensor Watch and Sensor Watch Pro, which replace the PCB in a classic Casio wristwatch with a new board sporting a bunch of sensors that add functionality. But Castillo's first attempt at making open source hardware was an effort to design an open source Amazon Kindle alternative.

The Open Book Touch is an eBook reader with a small, front-lit E ink display, a microSD card slot for storage, and support for EPUB and TXT files. But what really makes it different from most eReaders is that it's a fully open source device with unusual (for eReader) features like a user-replaceable battery. Not only does it run open source firmware that can be inspected and modified, but developer Joey Castillo plans to release the hardware designs once the eReader begins shipping, allowing anyone to 3D print their own case or make other changes.