We always try to give stuff that can be used up. Art pads, scratch art, that sort of thing. So we expect things to not stay forever.

Of course we live in a tiny NY apartment and so do our kids friends, so that colors our choices.

Space based mirrors for asteroid mining. Bounce a sh*tton of light from the sun around and just melt asteroids. Love that in the Troy Rising series.

Lots of problems getting there irl (need a better way to get out of the gravity well, and light speed lag for command and control would be a real issue) but the idea is just too fun.