Video: Modding a Game Boy to add a retro game console is nothing new. However, one modder took it to the next level with a working cartridge and removable battery pack. As you can see in the video above, modder wermy opened up a classic Game Boy cartridge and added a microSD-to-SD card adaptor. He then soldered the contacts from the adaptor to the old cartridge contacts directly. Inside the Game Boy, he also soldered the cartridge reader contacts to the Raspberry Pi. The result is that the cartridge became a removable adaptor for a microSD card, which should be super handy for changing out games.
The mod also includes other nice additions like a removable lithium ion battery pack inside the battery compartment (naturally), as well as L and R buttons in the place where the middle screw holes used to be. You can check out the full build at the source below to see how he did it.