After the tail pieces cure, trim the edges of the sheeting to within 1/16". Sand them flush with the core with a long sanding block. Take extra care not to sand into the core itself, if you do you'll alter the shape prematurely.

Now mark 1/4" in from the trailing edges and cut away with a sharp x-acto knife (or band saw if you prefer). Trim outside of teh marked line, and sand to it.

Here is where I differ from a few people. In general, the stock you'd buy for leading edges and such are made from the heaviest wood they have. The stuff is like iron. Instead, I take a piece of 4-6 lb stock and make these pieces from them. You can save a few ounces on your plane if you do this. If you're a "tail stander" don't do this for the LEs of the stab. They will crush. But for TE, and wing and fin LEs it can save a lot of weight.

For the fin, glue a piece of 1/4" balsa to the TE, and a piece of 1/2" balsa to the LE. Use polyurethane glue spread really thin. Wipe up excess with a paper towel. Hold in place with masking tape.

For the stab, use 1/4" on the TEs and 3/8" on the LEs.

After they are dry, mark a center line down the LEs and sand a contour to this line. Sand the TEs flush and leave them. They should be at LEAST 1/8" thick, possibly more.

The tip for the fin/rudder is a piece of 4-6 lb 1" sheet. Glue this in place and then sand to a rough contour when finished.

The stab is the same, but make the block tapered: 3/8" at the LE, 1" at the TE. Again sand to rough shape.