Dear shapeway users, Recently I wanted to print a chess piece of mine in the new ceramic material. The model past the initial test and it could be printed in various materials. However, the shapeways' website would not let me select any of the ceramic materials. The website simply stated "not printable in this material". I tried making it hollow, but that does not seem to do the trick. Does anyone know what parts of my model need to be changed in order to make it viable for printing in ceramics?