clay, rubber, wax, sprue!

50/50 to make the rubber

 the rubber mold once the clay has been removed and the wood frame

 wax melting to 120 degrease, then poured into the rubber mold

 The molds are sprayed with adhesive

 then tied with rubber tubing

 then buried in a sand pit

Lastly the wax is poured into the rubber mold to then let dry until a 1/4'' wax wall lines the interior. I then pour out the remaining wax back into the melting pot

 The clay ribs and sternum abstraction

 the piece is cut into four parts to be casted

 The wax spinal disk came out great on the third try

 To then make the sprue's, I had to use a plaster mold and pour in wax to create a thick wax channel for the bronze to flow

 wax sternum

 small part of the ribs, made with a simple silicone mold