How it's made. Every box is made open and flat, lid and base in one plane with a pin already through the hinge - nothing is assembled and nothing is glued. The knuckle bores are teardrops, not circles, because a round hole printed on its side sags and seizes the pin. They nest half into half, base inside base and lid inside lid, so eight boxes take the space three otherwise would. PETG: the hinge is the part that gets worked, and PETG bends where PLA snaps.