The repair of FRP bumper is very simple. 1. Use a grinder to remove impurities (reverse side) inside, until it is completely white. You can repair it with any tool. 3. Chop the felt paste with resin. 4. After curing, smooth the cracks on the outer surface with sandpaper and scrape them with putty. 5. Use fine sandpaper to polish putty until you are satisfied. 6. Find a self-painted spray with the same color.