No tooling required plastic enclosure manufacturers
Smartbox offer a very viable alternative to machined off the shelf plastic enclosures. These guys will bend and machine sheet plastic to make fully customized enclosures without the need for any plastic moulds etc. Using different plastic materials and shaped edges you can end up with a really attractive looking enclosure for the same or lower cost than using a nice off the shelf enclosure. Setup costs are not high (very low if you can provide a drawing or model of what you need) and they can manufacture 1off prototypes no problem and then no minimum order quantity production batches. Snap together plastic cases are a bit of a specialty, but screwed together is also no problem for them using threaded metal inserts into blocks of plastic that are welded in.