I've been thinking about this sort of thing as well. As far as I can see there's a few options:
- FDM printer: Can look "ok" if you're very good, but these are at best for one-off or don't-care boxes IMHO. The repeatability isn't great if you're after high quality, but it does let you run off something in hours rather than days for a prototype, and you can hone the 3D model to make things fits etc.
- SLA printer. These have grown in capability over the years, I've got a People Phenom L and it's truly amazing what this thing can produce. Downsides to SLA are that the resin is toxic when liquid, and it "feels" a little weird. It's also just as finicky and runs can be just as non-repeatable , but the end product looks a lot nicer (difficult to tell it was 3D printed) and you have the same time-based advantages for prototyping
- Outsourced 3D print - I haven't tried this (I have the above Phenom) but there are many places you can send off a model and get back N copies of the model - every time I looked at it, it seemed expensive for what it was, especially if you were after SLA-levels of looking nice. It does offload the the-darn-thing-didn't-work-again to someone else, though

- Choose a standard case - possibly customizing it with some silk-screened printing. This is the bare minimum for anything you sell, IMHO, and there's a fair variety to choose from, but there's no real hiding that this is what you did. If you're after the upscale-look this isn't a viable route unless you're *very* lucky with the match between your requirements and what's on offer
- Tool-less enclosure manufacture, like these folks. The last time I spoke to Dan (which was admittedly a while ago now) the cost of a relatively simple box (8" long, w/ cooling slots, mounting bosses, cut-outs and structural supports) would be ~$500 NRE, $100 fee for silk-screen, and a run of 100 would be ~$25/box, so an all-in total of $35 or so per box. This is my preferred option atm for small-run. There are a bunch of these companies around, I think, the above is just the one I got in touch with
- Complete custom case manufacture - [ur=https://www.protocase.coml]protocase.com[/url] and the like. This can be anything you want, but you'd better have deep pockets. You pay for the flexibility with money. Lots of money, at least that's how it's panned out for me when I've specced out a trial box.
- Chinese anodized enclosures - there's a thread here regarding how one of the members of this forum worked with a Chinese manufacturer to get custom cases made
- Injection moulded - now we're talking real scale, this is perfect for plastic enclosures if you have a run of thousands, or tens of thousands. The NRE is the expensive part, and it's all up-front, to design and create the mould. I did look into a desktop-type moulding machine, but these seem to be (a) expensive for what they are, (b) limited in the amount of plastic they can inject, and (c) not particularly high-speed or reliable
To be clear, I haven't used any of the mass-production options yet - I'm still working through the design of the project I have "cases" in mind for, and since it's not the day-job, it takes a while. I haven't even (yet, though it's on the ToDo list) mocked up a case on the Phenom yet...
But I'd be interested in hearing about other options over the above, or if anyone has experience with them
