This was the dream, right? To go from bits, from 101001110011110000, to actual atoms, to sit at your computer and—just by typing—manipulate things in the real world. Like, for example, putting blocks on top of blocks, building bridges, toppling towers, just by tapping commands on a touch screen.

Eleven years ago, science fiction writer Bruce Sperling imagined how, from a distance, we might stack, assemble, and disassemble not just tinker toys but also “big hefty skull-crackingly solid things that you can pick up and throw.” Making digital information physical, he said, is “the world that needs conquering.”

Well, sound the trumpets. Or maybe the piccolos. The conquering has begun. And in the most charming way.

This month engineers at the