Nintendo has ported a handful of classic N64 games to its portable systems, such as Ocarina of Time making an appearance on the 3DS. But for gaming on the go, the N64's library is mostly unavailable. Modder GmanModz took on the challenge of building an oversized replica of the clamshell Game Boy Advance that’s large enough to accept and play actual N64 carts.
Reviving classic games on modern hardware is typically done using emulators that rely on powerful processors to recreate classic consoles through software. Throw enough processing power their way and the experience can be almost seamless, with smooth gameplay and rock-solid frame rates, but some consoles emulate easier than others. The N64 is one of the most challenging, which is why GmanModz’ approach is arguably the best way to guarantee his portable N64 experience is exactly as he remembers it on the original console.
Starting with an actual N64, GmanModz undertook one of the most thorough trimmings of the original electronics and motherboard inside it, which included extensive rewiring to relocate a chip called the PIF which is responsible for interfacing the motherboard with controllers and the security measures employed in game cartridges. (Region locking.) The extensive miniaturization of the N64's guts allowed them to fit inside a custom 3D-printed housing that was inspired by the Game Boy Advance SP: the clamshell version of that portable that mercifully included a much-needed sidelight. (And eventual backlight)
GmanModz’ N64 SP includes a much better LCD display than Nintendo ever included on the GBA SP, and some may argue, a better control layout than what was offered via the N64's odd three-pronged controller. However, while the N64 SP includes shoulder buttons and an analog joystick, it’s lacking the pistol grip style Z-trigger which played no small part in making Goldeneye as enjoyable as it was.
If you want to sacrifice the N64 that’s been gathering dust in your parent’s basement towards building your own portable version, you’ll have to wait until GmanModz provides a more detailed breakdown of this mod on his website. The video he shared on YouTube does delve into some of the specifics, but at just three minutes long it’s not detailed enough to tackle such a technical build.