Custom Enclosures

I have been working on a product that requires a custom enclosure. I have experience in SolidWorks so I can design it myself but I noticed that Sparkfun offers design services and I was wondering how they get the design made? At first I really want to get a few single units made for as cheap as possible and then I’ll get a bunch ordered. If sparkfun doesnt actually build it but just designs it, can anyone recommend somewhere I can get it made?

Thanks,

Brandon