These are the parts / sources I'm using for stock / replacement GBC membranes and buttons.
- Silicone pads for gameboy color (1)
- Silicone pads for gameboy color (2)
- Gameboy Color Button Plastics
I found these parts (and others) on this excellent resource: List of places to get buttons and membranes (consolemods.org)
I Explored using Joycon buttons / membranes, but they are unfortunately too short to match well with the height of the ESP32-S3-BOX and BOX-3: