Show HN: I built a synth for my daughter

> A 3D-printed enclosure is fine for a prototype, but a real product likely needs injection-molded parts, which require expensive tooling.

For kid-friendly toys, yes. But for older users not necessarily:

https://teenage.engineering/products/po

Wood is also pretty child friendly.

But neither injection molding nor carpentry will protect a synth from a child dunking it in a puddle of water.