I'd tried Starwars Galaxies (a friend roped me into it)... I bought a 3 month chunk of time, scanned the EULA and saw the typical "We'll change the game, if you cry tough crap" disclaimers, etc. If you don't login for 30 days the account goes inactive... So, bored with that POS game, I let my account expire. And got a bill for another 3 month chunk of time. Burried on their website was a clause stating that unless you specifically cancel, you are rebilled whether the account is inactive or not. They may have gotten US$55 out of me, but they've lost hundreds in other stuff where I've deliberately gone with a different brand... even if it had lower specs. I still have a few square inches of my butt reserved if they'd like to kiss it. But I'll never get anything made by Sony again.

ANYWAY. THUMBBOARD.

Typical keyboards work via what's called a scanning matrix, the output from which is fed to an encoder which translates the signal into something the computer will understand.

The matrix is laid out kinda like the game battleship:

. 1 2 3
1 A G R
2 L M N
3 E C Z


Basically if the key(switch) 1,3 is closed, an R will result. If 3,2 is closed, a C will result. Reading up on MAME cabinets people have made leads to some problems, blocking & ghosting. These only occur if multiple keys are pressed at once (excluding ALT, SHIFT, CTRL modifiers) which I don't think will be an issue.

Pin 25 on the PCB is ground and everything must lead to it. The other 24 pins represent "co-ordinate" locations of the matrix. Now, assuming I could gut a USB keyboard with a PCB small enough to fit into the proposed thumbboard case, there would be a TONNE of soldering wires from the PCB to the buttons. I think it'd be messy inside but it would fit. Popping a battery in there too would be really hard (I think toughtfix's plans call for a 9 volt). I don't think the slide-in-case design is going to work real-estate-wise. I think making the case the same shape as the 770 but a little wider (so the 770 slides into it and not the other way around) is the way to go.

Basically, looks possible.