
Son, have you tried the reduce detail brush? That may help a little, I think Dr Petter has a good idea on how to improve the speed. I do find the key mapping a little strange, would also be nice to have controls to alter the brush size, i.e. middle mouse scroll to adjust. Maybe one day...
James, I'm looking forward to seeing the physical sky renders

Wikki, I've only had a few minutes play time with it but apparently you can alter the mesh material, I would assume there would be waxy type materials, etc... Have you come across this? Are you planning on getting your Prof into Octane?