Jason has a working prototype for what he calls a openSip+puff. It’s meant to be a controller for people with disabilities. It will allow you to do things with your mouth by sucking in air and blowing out air.
It uses a pressure sensor and an ATmega32u4. It connects as a USB device so it can end up being a keyboard or mouse device (or some sort of button trigger or joystick). I think the code is still being hashed out but he’s making good progress.
It’s open source hardware, and he’s hoping to do a Kickstarter soon.
Check out the rest of the article and source code here.