[brk]

I would guess an extremely low percentage. What was the last item you bought that was essentially nothing more than a single piece of some kind of plastic?

3D printing has an arguable use-case (IMO) for 1-off plastic-y parts, but it's far from making anything overly complex or durable. When you think about any object that might have a market need for 1000 or more of the same thing (not a very large number) injection molding turns out better parts at an arguably lower price.

I like the idea of 3D printers, and I've played around in the past with vinyl plotters I've modified to cut wood veneers, and small CNC machines and the like, but I just can't figure out how to justify a current 3D printer beyond a novelty aspect.