To find the grain on a cardboard or wooden jigsaw puzzle piece, tilt your head and look at the pieces at an angle. The “itty-bitty straight lines or bumps” you see are the grain, Jill says.

he was putting together 500-piece puzzles. He turned professional about 10 years ago, spending long days guiding pieces of wood into the stationary blade of a scroll saw. “It’s very much like ...