The modder, who goes by the online handle "dekuNukem", demonstrates in the video above that the controller works seamlessly as an input for Super Smash Bros for 3DS. Details on how to mod the controller have also been published.
However, the add-on requires a number of unsightly changes to the hardware, including an exposed circuit-board on the base of the device:
To build the mod, which will likely invalidate Nintendo's warranty, players need to purchase an assortment of circuit board items such as a 1K resistor, a 330 Ohm resistor, 2N7000, a 1uf capacitor, and various pin headers.
But mod enthusiasts who persist with building the tech are rewarded with a responsive GameCube controller input, complete with buttons that can be remapped on the fly.
Since Smash Bros release in Japan on September 13, along with the western release of the game's demo later that month, some players have broken their 3DS analogue sticks (officially called the Slide Pad) due to the game's vigorous demands of controls.
Super Smash Bros for 3DS launches across the US and Europe on October 3. A release date for the Wii U edition has not yet been confirmed.
Rob Crossley is GameSpot's UK News Editor - you can follow him on Twitter here