I've made a fake medical scanner which goes through the motions of scanning a sample in a test tube you drop into it. So far, that's nothing particularly interesting. What I've added to it though is a 'GM interface' which can be accessed over Bluetooth.
The photo on the left is where I mocked it up using some breadboard. In the end I used a bigger screen and there's an Arduino Mega inside as I needed the extra pins for bits and bobs. The Uno really doesn't have the memory or flash space to handle driving the display if you use the very nice libraries written by Henning Karlsen.
Once the sample is loaded a GM can connect, set what the outcome is and how long it takes to process. There's a facility for them to type free text and it just outputs it on the screen at the end. I still need to do more work on the software so it handles events in a less linear fashion but I think it's coming along nicely. It better be, the LARP is on Friday.