I've started on the biggest seat part, the main side frame. Since the silicone mold making seemed to work well for my first try with letters, I thought that it might allow me to make the most intricate part of the side frame pattern, the open basket weave. I backed up the weave area with a waxed piece of acrylic, and brushed on a thickened silicone mixture to make the mold. After curing and peeling it off, it didn't seem all that great, but I decided to go ahead and make an epoxy casting with it, to at least learn something. The basket weave is on a curved surface, which doesn't lend itself to making an epoxy casting very well. So I flattened the silicone mold, and put plaster on the back side to keep it flat.
I made a dam around the silicone with molding clay, mixed up epoxy and poured it yesterday. I unmolded it today, sanded down the back side to get it to the correct thickness, and did a little clean up with a paring chisel and files. I am very pleased with how it turned out. No need to do it again.