From Shapeways "Also, the note on the rejection from production on the iron man head was as follows: “The areas noted in the attached picture are too thin to withstand our manufacturing process without breaking. They are at risk of breaking during the polishing process. All materials specified as dyed or polished are manually cleaned and then submerged in a circular vibratory tumbler full of thousands of ceramic pellets for several hours. Each pellet is approximately 4.5mm wide and 11mm long, and will exert a slight pressure on all sides of your model during polishing. This can cause some wires or walls to break. The larger the model, the thicker the wires and walls must be to support the overall geometry and the pressure around the model during powder removal, as well the weight of the ceramic pellets during polishing. Thickening the areas shown in the picture will decrease the possibility of the model breaking during the polishing cycle. We encourage you to iterate on your design to ensure a quality print.”
I'll post a picture shortly
