The process I used to cast the legs for Sabela is pretty much the same in theory as the one I used to make the head. Basically I created a latex skin, and filled it with soft Urethane Foam. You can read all about that final foam casting process for the head here.
Step one to making these legs, which is creating an armature with rare earth magnet feet, is here.
I made the legs a little differently than the head, though. First, I found the leg mold cavities too narrow to coat with latex while closed, as I had done with the head casting. So I brush the latex into both halves of the open mold instead.
- First I added a third strand of armature wire (1/16″) to the 2 that were there before, and twisted them together. Then I inserted a bit of that 22-gauge jewelry wire (pictured in the rare earth magnets post) into the heat-shrink tubes, and wrapped it around the 3 strands of armature wire. I’ve learned to add this jewelry wire to all my armatures as a backup for when the main wires break… so I’ll have a little more time with the puppet before I need to replace it. After the armature’s done, I set it in place inside the mold, and mark off where the heel ends, either side of the knee, and the top of the thigh. These markings give me an idea where to leave the armature wire free and bendable in the next stage.
- Once I have the knee, ankle, and hip joint marked off, I fill in these spaces (basically the tibia and fibula / femur bone areas) with plumber’s epoxy, providing solidity to where I don’t want the leg to bend, but leaving the joints open.
- I remove the armature from the mold, and brush 5 thick coats of liquid latex into the leg cavities. Each coat needs to dry fully before applying the next. I try to be careful in the feet, not to build the latex skin up too thickly, or else the armature won’t fit into those areas.
- Finally, I place the armatures back into the mold. I brush a very liberal amount of latex on the edge of the molds, onto both halves… making sure to cover both inside the edge AND outside the edge. This will create a pretty heavy seam on the legs when they’re demolded, but that’s OK — the seams will be removed. The heavy edge coats just ensure that the halves of the skin will meld together.
Then I bundle it all up with the elastics and that nice yellow strap, and let the whole thing sit for a few days. There’s not much airflow going into the mold, so this one takes longer to cure than the head does… 3 or 4 days is usually pretty safe. Then I do the urethane foam casting as described here.