So, here's my skull paperweight, based on computertomographic (CT) images of an actual human being. The last image was taken through the opening in the base. Base diameter is 90 mm, height 65 mm, and weight 696 g.
Which technique was used? The "lost wax technique" (or more general "investment casting") has been mentioned to me. Now checking books and the internet on these I understand how this works for outside shapes, or simple inside shapes (like some vases), where the cast can be pulled out. Just pulling out will obviously not work, however, for a structure like the skull, where glass would fill in sort of ducts within the cast.
I know from medical applications that 3D models can be built from 3D data sets (like CT images): is there some material for this, which is sufficiently heat resistant to be used as mold for glass - and then be dissolved chemically?