Have you considered casting your enclosures out of a mold?
The business that I work for made a lot of their enclosures using this method.
An initial model is designed and printed on a 3D printer , according to the board size, specs etc.
And then from the printed model a mold is made from silicone (Moldmax was the one we used).
Once the mold is ready , resin can simply be poured in (You'll have to do some research on what resin will and will not work for you) and after a few hours of curing , the newly molded enclosure can be taken out and finished off for a spray job.
Not all designs are ideal for this method, as there are certian specs you need meet (like making sure the enclosure is taper etc.)
Hope this helps a bit. 