The current pricing FAQ says: "How is your pricing calculated? Our pricing is based upon the actual amount of material used in your model. So the actual volume of your finished object not the volume of the bounding box. The model detail page has the pricing of each model on it. All prices include shipping and handling." The first sentence is not true. The pricing, at present, is based on the predicted amount of material, based on the sum of the volumes of all objects in your model. This predicted amount can, in principle, deviate wildly from the actual amount of material used, because objects can overlap arbitrarily, leading to double-counting of volume. In other words, the sum of the volumes (upon which pricing is based) is larger than or equal to the actual volume of material used when printing a model. The FAQ should be updated, preferably with the second sentence of the above paragraph. I think it would also be extremely valuable for some talented member of the Shapeways community to develop an algorithm that better approximates what SW wants, which is the actual volume of material that will be consumed during printing.