Okay Richard here goes,I built my stab/elevator just as you did. After cutting them apart I used a 48" piece of aluminumangle clamped to a 48" building board as a guide to square up the stab trailing edge and the elevator leading edge. The guide was clamped over a piece of 180 grit 3M sand paper that comes in a 3" wide roll with an adhesive backing. I usually keep a roll of 180 and 320 around for any number of finishing purposes. Next, there was no 3/4 X 1/2 trailing edge stock for the fin, but I guess by now you already know that from Jeff's thread. I just went ahead and used the 3/4 X 3/4 piece by marking a center line on the inside and outside with corresponding center lines on the ribs. Line up the center lines and CA them together. Of course this requires a lot of sanding to taper the fin into shape, but who cares it's a Simla. Finally, I use an automotive product as a filler. It's Evercoat metal glaze, but don't let the name fool you, it's light weight, adheres well, and can be rough sanded with 80 grit paper and finish sanded with 180 grit paper. I usually brush a couple of coats of urethane clear over the area that I'm going tofill since the Evercoat glaze is much harder than the balsa. After the clear dries I scuff it lightly with 180 grit and then apply the glaze. Sand to finished shape with 180 grit and you are ready for primer.