I bought a Raspberry PiFace Digital 2 board and thought I'd play around with it by creating an OctoPrint plugin to support it.
Not sure how I want to present all this to the user. I'm guessing that it might be interesting to later allow some sort of Scratch-like or ladder programming to it.
It would be good to know of some use cases you might envision.
It's got eight open-collector outputs (eight LEDs and two relays within that space), eight inputs (four push buttons within that space). It can be powered by the Raspi; it can provide power to the Raspi or there can be split power as well. There's a mode so that the outputs can be above 5V.