'Half-lap joints' only seem to pertain to woodworking, and it doesn't seem to be the same.

'Cardboard dividers' doesn't seem to go anywhere.

Uline says they're called 'egg crate dividers', but they don't know why, unless that's how they used to separate eggs before the day of the molded carton.

'Interlocking puzzles or cardboard' doesn't go anywhere, and those thin wooden dinosaurs are the only things I can find.

There is an old book on 'slotted cardboard', so maybe that's all there is.

Thanks for the ideas.

Sue