Products, personal builds, and commissioned models. Some are for sale, some were made once to find out whether they could be.
Modeled from scratch, printed light enough to forget you're wearing them.
Chassis rebuilt from printed parts, iterated across several failed versions.
A long-run build in printed sections, assembled and finished by hand.
Commissioned models and UGC produced for an independent dev team.
Most of what gets made starts as somebody's description of a thing that doesn't exist.