OK, update time.
I've designed a PCB, paid for manufacturing and I will probably send the design off this weekend. In theory that will get me 10 PCBs so I will have about 9 of them for sale for about $8 each if they work. I want to get the finished PCBs back and tested before I post the files on my website so given manufacturing turnaround times plus the fact that I'm 15% of the way through scanning 100 rolls from my holiday (some photos from the night of my previous post) means it will be well into November before you see much. If you're keen to get started, I can email you a PNG of the schematic and some new source code - PM me.
For prototyping purposes I just used a breadboard as you can see in the video. If you don't want to buy a PCB, you can easily construct it on a "prototype shield" (eBay). For a box, I would recommend a rectangular ABS or Al case and I'm using this one (99x125x40mm), which is about as small as you can go and have it all fit.