Finished the enclosure by covering it in metallic paper.  Take a look at the results here: 

At a craft store I found 12"x12" sheets of metallic paper on thick cardstock that ended up working great.  The thicker size of the material helped to smooth out imperfections in the cardboard.  For attaching the paper I used Super 77 spray glue so it's a smooth, permanent finish.  The only difficulty was working with the glue.  You get one shot to line things up and that's it!  Also cutting the curved shapes and edges was a little challenging--a very sharp knife is required.  The edges aren't perfect but I'm still very happy with how things turned out.