This is just sharing the Sega Genesis 3 Function Restore Helper Boards project by Consoles Unleashed, from https://github.com/consolesunleashed/sega-genesis-3-function-restore-helper-boards. All design credit goes to the original author.

The Genesis 3 shipped with several functions removed, and restoring them means running wires from the cartridge port to the main GOAC chip. These thin boards solder straight onto the cartridge-port pins through castellated half-holes and break the needed signals out to large, clearly labelled pads. On VA1 consoles this restores 32X, Virtua Racing, Game Genie and Master System support, while on VA2 it restores Virtua Racing and Game Genie.

There are four variants: VA1 Standard and Mini, and VA2 Standard (with Triple Bypass audio pads) and Mini. The boards carry no components, so no assembly is needed. The author recommends 0.6 mm thickness, blue solder mask and castellated holes.