They're intended to be laser-cut, which limits the materials.

Those flaps and wheels really want to be injection-moulded from ABS, with round pins at the flap ends. That would be cheap if you were making enough of them.

(I miss TechShop. They even had an injection molding machine good enough to do this.)

yes i very much miss TechShop. i was a lifetime member. too bad they tried to grow too big, too fast. i think they misunderstood their business, at a fundamental level.

the techshop 2.0 guy was a travesty.