Just finished up x0xb0x #3. All of the basic functionality seems to work and it sounds just like a 303. Well, better than a 303 in my book but I guess I'm probably biased.
They gray knobs were special-ordered from Korg Europe. They were made for the Electribe ESX-1 and EMX-1 but they happen to be perfect for the x0xb0x. I could have ordered the large switch knobs too, but I would have had to hack the encoder shafts even more than I already did.
The top panel is a standard Adafruit x0xb0x clear acrylic panel. To make it awesome, I just sprayed the underside with black paint. I wanted to use vinyl instead, but the paint turned out to be so much easier. Looks great, the only downside is that the panel came with some scratches from the store. Oh, and it's a friggen fingerprint magnet. Next time, I may take a drill bit and scrape out the LED holes a bit so that they light up the laser-engraved letters on the panel.
I used a clear I/O panel this time, so the innards can be seen without taking the x0x apart. I think I'll go back to metal unless I can devise an easy way to get an LED or two in there for show. All I have left to do on this one is tune it, perform a full function check, and hack in a power switch and then it's eBay time!
I posted the innards of this x0x in a previous post here and did a writeup on x0xb0x #2 here. I hope to put together a video of me rocking the x0x sometime this week or next.