Ben,
There was a prototype built of the Atari Flashback as a portable:
http://www.joystiq.com/2007/06/27/a-peak-at-the-atari-flashback-portable-prototype
I would think it would be a cool one episode build idea. I'd even be open to getting a Flashback 4 (most current version with the wireless joysticks) if it would help
Maybe having it with a video out similar to the Sega Nomad so you could use it on a TV or as a handheld (OR...... Like a Wii U, and one person playing on the handheld and the other using a wireless joystick on the screen ???)
P.S. I do want to say, I loved your Sinclair ZX build. As someone that had a Timex Sinclair 1000, I know the multiple key issue!
