To put it plainly, this portable gaming device is capable of supporting Game Gear and Master System titles, and you need not exhaust your rechargeable AA battery collection, since it sports a built-in rechargeable battery that plugs into an AC outlet whenever it runs out of juice. The major drawback for this DIY project would be its rather hefty two-plus pounds of weight.
Definitely not something you will tote around to keep you entertained these days, especially on a long commute, but it is worth a look if DIY projects are your cup of tea.