If you hang out often in the community console modding, you have already heard of GManModz. This boy has in his curriculum various projects including portable versions of various Nintendo consoles, to which today is added the Nintendo 64.
The console N64 SP (which incorporates both the name and the forms of the GameBoy Advance SP) is just what it seems: a reduced version of the console, obtained through a cutting the motherboard of the console. This not only guarantees one small size, but also the maximum compatibility with games, since we don't talk about any kind of emulation. Finally, not only can you use your own original cartridges, but you can also check the status of the battery through a dedicated card located on the back of the body (obtained through a 3D printer.