Step 1: Materials
The stock rudder is about 5/8 inch thick with a 3/8 inch diameter shaft. I bought a piece of 3/8 inch stainless steel rod from a metal supply store and balsa from a hobby shop. Two part epoxy resin and 4 oz. fiberglass cloth were left over from another boat building project so I used that.
Step 2: Rudder shaft and rough shaping
These measurements were traced onto a piece of 3/8 inch thick balsa. The stainless steel shaft was bent and drilled then placed over the balsa and the outline of the shaft traced onto the wood. Balsa is soft enough that cutting out a channel for the shaft to fit into wasn't hard. I used my table saw to cut out the rough shape and a utility knife and Dremel tool to cut out the slot for the rudder shaft to fit into.
After the shaft was fitted into the balsa, I taped it off, mixed up some epoxy and poured it all around the shaft to lock it into the balsa. Let it cure.