The companies below use either beetles or maceration for skull cleaning. These are the preferred methods over boiling which if not done properly can cause damage to the skull and teeth.
Rhinoriginalz
Ryan Hein
Drop @ Steve's Meat Market
Arvada, CO
303 427-0113
Artiodactyla Trophy Services
Jim Coker
Morrison, CO
303-808-7902
Classic Antler Mounts
Marty DeMoss
Aurora, CO
720-256-4810