Thanks guys
Nice, what's the process for programming the printer?
This depends on the printer, the Ultimaker accepts different 3D file formats on an SD-card. You insert the card and print it. My friend created the cone programmatically after we determined the arc from images taken straight from above. Then sized correctly – without factoring in the material we'll take off while polishing – exported to the correct format and off it goes.
Cool part is that you only specify the outline, then tell the printer how much you want the inside filled. We selected 70% or 80%, the printer will then fill the insides with a honeycomb-like structure that you can see on the first image in the link. It took about 20 minutes to print one cone. If anybody wants the 3D models I'd be happy to post them here.