NICE knife, as always, but I'm curious how you keep from getting bubbles in the casting resin? Vacuum bag, perhaps?
I use a large (1 gallon jar) as a vacuum chamber
---put the cut up skull (or other material) in smaller container with the resin
---put the smaller container in the jar
---seal the jar
---turn on vacuum pump (must cycle it several times to get desired results)
The trick (learned through trial and error is to shut off the vacuum pump before the resin starts foaming. If it does - its ruined. Usually 3 to 5 cycles with the vacuum pump is enough.