A 2-oz canister of Play-doh costs about 54 cents. (Less if you buy a case of 48).

When I was littler, I worried a lot about keeping the colors separate. Because it would, perhaps, ruin them if you mixed them up. Ben was over last night, playing with Grandma Nancy.

He had the black Play-doh, which was another color and black a couple play sessions back, but it now all black. And he had the yellow. They were piled together, squeezed through a couple of presses and a rolling pin.

“It...