I posted a 3D design file for a couple of enclosures today. Included is a 3D design for an Arduino Pro Mini enclosure. We were selling the design as a product on Ponoko but the cost of the print was ridiculous. Actually the cost of the prototype was ridiculous. 3D printing the case on superfine plastic isn’t cheap but is more reasonably priced on cheaper plastic. If you have a RepRap this design will suit you nicely. I’ll post some pictures on here and Ponoko very soon.