I designed a 3d printed shell that makes the Gameboy rumble cart as small as possible and also keeps the rumble functionally. The PCB taps into the the VCC and GND and PIN 26 of the MCB5 mapper chip of the cart and powers the vibrate motor. More info can be found at the blog post below.
Blog post - https://facelesstech.wordpress.com/2023/08/26/pokemon-pinball-without-the-battery/
