Once the second application of filler had been cut down with 80-grit and the DA sander, more finish work was done with 80-grit on an air-powered longboard. Leo used regular black spray paint as a guidecoat; the layer of black makes it easier to discern the high and low spots while sanding. At this point, any flaws in the repair should be minor and easily repaired with sanding. If further hammerwork or extra filler is needed, it means you werent thorough enough in previous steps. A third layer of filler should never be needed.