It’s written in the Adobe PhoneGap (Cordova) platform with Framework7 for the styling and scaffolding. It communicates to the underlying OctoPrint interface inside the printer itself. Rather than building several smartphone apps and being subject to the recurring annual developer fees by Apple/Google/Microsoft, I intend to serve it up in a more economical way: embed another single-board computer inside the printer.
This will fit nicely on a $10 Raspberry Pi Zero W computer, as shown. It’s then powered by the USB 5V supply inside the printer and would be powered on every cycle. I’d then use my iPhone’s or iPad’s browser to simply connect to the app.
The app is fully-functional for the Robo C2 printer and sports a slick-looking interface.
And here are some obligatory screenshots of the app.