The black acrylic has different print settings than the standard white strong material. Shapeways will let it print in white strong, but not with the acrylic. I think it will print fine since I've made all of these on my FDM printer, the piece they claim won't print right is the small barrel and the connections to the sprue.
I've been meaning to update all the models, but have been too busy at work. I'll try to upload just the mirage rifle.