After reinforcing the leading edge of the flap, today I checked the fit to the wing trailing edge. It fit pretty well, but needs more micro. Not a whole lot more, but some. But the main work tonight was to fill the trailing edge of the flap. Got it done, but I'm not really happy. The bottom of the flap has a bit of concavity, and because I had to add a bit to the trailing edge, filling it with micro tends to accuntuate the concavity. To fill the entirety of the concavity would add way too much to the weight of the flap. Does the concavity matter enough to sacrifice the weight?