I wish when Shapeways show you a picture of the the print and not the screen shot, as I have found when it comes to complex curves all printers have there problems and the frosted finish is no exception.
My experience is to get the finish right it takes a bit of work.
think in the other way about the 3D print technology.
With the 3D print you can "technically" create a negative form(s) including venting pipes and used it to do the resin.
Would be interesting if this was ever done