I'm often asked for things I'd recommend for "the interested reader",
whether they be students or adults. Here I list things people have
suggested would be suitable for me to recommend, or at least to mention.
build light-based computers by assembling beam splitters,
reflectors, filters and optical transistor type gadgets.
Sokobond (on Steam):
chemistry-themed puzzle where you need to assemble molecules
by pushing atoms around, encouraging the ones you want bonded
to join each other and avoiding creating bonds you don't want.