I love sculpting! It's one of the most fun and rewarding parts on the production that on commercial work I never get a chance to do. For Gregor's head I started again with some very rough thumbnail drawings to find the shapes. I looked at some Russian royalty from the olden days and used that as a basis. When I had a few things that were starting to work I jumped right into the sculpt. I used sculpy because I wanted to be able to sand it down and make it really blocky in places.
Gregor will need replacement mouths, so when things were starting to get close, I cut his mouth off and worked on them separately. After some sculpting, baking and sending the mouth fit pretty well into the head. I put some half spheres in the back of the mouth and then propoxy into the head, pressed them together and then pulled them apart. This gives the mouth registration so it will always lock into place.
I took the two pieces and made a silicone mold of each. In the head mold I roto casted some plastic. Basically I wanted the head to be as light weight as possible. I filed the face half of the mold with the two part plastic, quickly closed up the mold and rotated it until it cured. A good trick my friend Scott showed me for this is to leave a little of the plastic mixture in a cup so you can see when the plastic has cured.
For the mouth, I casted plastic into the back of the mold (where the registration spheres are) and then pressed fresh sculpy into the front of the mold. Then I sculpted the mouth into the correct position. I had some sanding to make it fit, but not too bad. There will be big seams on the face where the mouth meets the head, but as I've said before, I love showing the process in the final product as long as it's not distracting. I am making a puppet film after all.