The Japanese artist Toshio Iwai, who is responsible for the 2005 DS title Electroplankton, also made a music composition tool (likely around 1992) called Sound Factory that was designed to be bundled with the SNES mouse. However, it was never released as the SNES mouse was shipped with Mario Paint instead.
It hasn’t been seen or heard of since. However, recently a prototype version of Sound Factory appeared on eBay, and the buyer who went by the name “KiroBomber” has released it publicly for everyone to check out. You can download it right here.
As you can see in the video above, it lets you use the mouse to create music through playing a number of mini-games. The official box art read: “Craft exciting melodies and interesting illustrations with Pix Quartet, play against the clock and beat out the music in Beat Hopper, create beautiful harmonies with the stars in Star Fly, and use Ice Sweeper to improve your coordination skills.”