I am starting to get more ideas for this project, most of them will eventually require a USB HID-joystick. Making one of those is one of my goals.
I usually like to design and make my own PCB's but this time I decided not to. The hardware will probably be an arduino pro micro, it's too cheap to ignore and precisely the hardware I would make if I did it myself. But I don't know if I'm going to use the arduino software. Usually I write in assembly, but creating a whole USB compliant device in .asm might be a bit too much. However, my last C project was a long time ago (not counting the first prototype in this project) and I don't have any experience with the arduino language (don't even know what it's called). I think I wil continue modifying the atmel appnote to get a basic HID- joystick.
My idea for a third build involves more non-electronic hardware.