Ah nostalgia. An enterprising individual over at the BenHeck forums has “basically cannibalized a OneStation” into an old NES cartridge that runs on three N-cell batteries (commonly found in certain scientific calculators). The innards of the cartridge house a 99-in-1 chip which should provide nearly endless hours of entertainment and contain most of your favorite NES games.
The batteries fit in the bottom of the cartridge and the Select and Start buttons are found on either side of the bottom notched portion. Looks pretty cool and the modder says, “Building it is actually pretty simple, nothing complicated just moving around components to make room.” Why not get started on your own, huh?