[duped]

Silk screen printing is probably the easiest way to introduce the concepts to kids. There are a lot of maker spaces/artist collectives and classes that have the basic tools and resources to do it.

[snek_case]

You could also try to replicate something like the Monster 6502: https://monster6502.com/

It's not lithography, but you can build a working processor out of small surface mount chips, and you can solder these chips with lead-free solder. That seems very achievable for a motivated engineer, and probably involves much less toxic chemicals?

[semi-extrinsic]

Or even gel plate printing, where you get to build multiple layers, one of them being a laser printed photo that is used as a resist.