The Gaston cast is sold as an assembled mount or as an unassembled kit (I purchased the latter). In kit form, the various parts require extensive cleanup. Most of the vertebrae are cast separately for mounting on steel rod armatures running through their centra, but they need to be drilled-out carefuly first. Due to the complexity of some of the casts (such as the neck vertebrae) a fair amount of filling and shaping may be required to fix distortions where mold sections misalign. You need to be fairly handy and resourceful to build this kit.