I have modded a Melotone Toy Drum, with very simple mods:
- External power supply (solder wires to battery terminals)
- Speaker On/off Switch (solder wires from switch to speaker)
- Audio Out (take signal directly from speaker)
- Trigger ins for Eurorack (simply connect a Jack to th epins of the IC, follow traces from pads to IC)
Here's the result, triggered by my Beatstep Pro: