I'm in the process of obtaining all of the required parts to build my Pocket Printer derivative. As stated previously, I am building mine with the standard 9x9"(ish) build area associated with a Prusa. This way I can use the Prusa Mk1 PCB heated bed.
I purchased the 8020 extrusions from Misumi. You can get it cut to specific lengths and have them tap the ends for you too. I will post more information as it progresses.