Maybe the " thermoplastic electronics enclosure" (btw. this sounds really fancy) he wanted isn't produced in the same size. Should he buy a block of wood/plastic/alluminium and make the case from this block?
You are wrong, and forgot a part of the description. Look yourself at the results and the costs, and see if it's sellable. That's what I was talking about. Don't bend it into something else.
Nobody cares witch 3Dprinter an enduser buys (consumes), nobody cares witch existing or selfmade design file is transferred. Nobody cares what the enduser "does" with the printed part.
The result is always the same: the owner had "fun", just like watching a movie. And there it stops.
For production and business the -10K "printers" are completely useless, and that's why the "Wow there grampa, don't get too cranky" screamers are plain stupid.
Also how quickly/economically can you prototype an enclosure/product with a CNC/subtractive manufacturing?
The same mistake here. Don't bend it from "sellable" to "prototype generation"
And don't generalise prototype. Are you talking about a dimensional demo, working part, witch material, specs?
These days, even the unfunctional prototypes in this area are made with stereolithography.