MAKING A DINOSAUR 

First the museum’s Pat Martin provided illustrations, and then in Toronto Research Castings produced a 1/8 size maquette or working model.  Head sculptor Ted Siwell sliced this working model into sections, which were enlarged and then made into Styrofoam matching sections of the basic shape.  To this shape was applied a layer of plastercine 1/2" thick.  The fossilized skin texture of a real dinosaur was the basis for a pattern on the model.  

Next  latex was applied to form a mold over the entire model.  The shape of the rubber mold was strengthened by a fiberglass support jacket, and for ease of assembly and future use the mold was made in pieces.  This mold was used to make the final cast of Dippy out of  colored gelcoat and fiberglass.  The cast is designed to be held together by a steel support armature built separately by metalworker Matt Fair, and then bolted together.  At the site, a  concrete platform supports the installed cast.    

Carnegie Museum of Natural History now has the finest fleshed-out model of Diplodocus carnegii ever made, and the museum owns the mold and the cast, just as it did nearly a century ago when the first fossil skeleton was cast.