Clean up your tools and skin using vinegar, which deactivates the uncured epoxy, and then soap and water.
The next morning I used a 120-grit disk on a hand grinder to level the whole business and blend the edge; the original epoxy residue and differences in core product made for irregularities in height, but nothing sands faster than balsa. A few moments with a finish sander evened it up and smoothed the edges; glass cloth must be laid over a smooth surface. I blew out the dust with compressed air and then smeared a bog over the whole surface, filling the gaps and radiusing edges; glass cloth must be laid over a continuous surface without gaps. This was followed while still green with 2 layers of 6-ounce finish glass cloth, covering the core and reinforcing the edge flange, which had always seemed a little weak to me.
The neatest way to trim excess glass cloth is with a razor knife while it is in a leathery state of cure. Finish sand when fully cured. Two coats of paint will finish it.
As for the other parts, it's just been a matter of painting, drying, sanding, and repeat. Should be on the water mid-week, since I want the paint good and hard before assembly.
It's surprising how the cost of materials adds up. This totaled just over $200 all in, about 1/2 for resin and the rest for glass, core, paint, brushes, and sundry materials. On the other hand, a new rudder assembly, if it were available off the shelf, would $3500 or so. Custom would be more.
If you like old boats, it really does pay to develop a skill set.