This week I had an interesting challenge in polyester finish repair. Repair a large chip of finish on the vertical face and corner of the arm of the piano.
The pictures really show the problem; and the results. The solution is not gluing in the broken out piece and then filling in around it. When does that ever work? The correct solution is building up the fill from bare wood to just below the final level with the gel poly. Then, after building a form or "dam" with plastic sheeting, filling it with the liquid poly.
The fun was shaping it all so that it looked like the original corner profile. Further sanding and polishing brought it all back to near original high gloss finish. A good couple of days work.