Just thought I'd share the results from some recent testing. If anyone is wondering how fine features can be with Sandstone material (current wall thickness limits being ignored), this image shows what I believe is the limit. The layers themselves are between 0.875mm and 0.1mm in thickness. A single layer of powder will have many tiny holes and gaps and cannot hold itself together well enough to get through the production process. However if one is extremely careful and uses exactly the right technique, two layers are sufficient to create a solid wall. Finishing is a whole other problem. This is not practical in most cases but it can be done. Another interesting effect is the transparency at that thickness. The words you see are written on the paper beneath the model. Since this model is shaded with ambient occlusion, the dithering pattern of the printer is also visible if you look closely. Very interesting!