(3) you make good looking gizmos which are not really worth copying seems to be the niche of “William”. Apparently the slides were about 150, and they’re externally simple but good looking. They’re out of stock but the shop has neat kinetic sculpture for high hundreds.

Could you get plastic versions for a third the price? Absolutely. Would you? Hell nah. I could see kits of spare parts to print and build your own, maybe, but not ready made.