1. Knock-out repair method: For small local bulges and depressions, single, small and shallow bulges and depressions can be repaired by knock-out method to deform the metal and restore it to its original state.

2. Prying roof repair method: pry open the concave part of the top with leveling knife (or spoon-shaped plate) and pointed tools (such as various picks) to gradually restore the concave part to its original state.

3. Stretching repair method: Pull out the dent with a retractor, which is also one of the commonly used dent shaping methods. The traction device comprises a sucker, a traction cylinder and a special traction device.