The joints made with a plastic welder are as strong as the material itself and are highly recommended for edge joints. In some cases the plastic welding rod can be cut from the material to be welded, which allows for the weld joint to become invisible. The simplest type welder produces a stream of hot air and can accept various different types of welding tips. Another welder heats up the edges of each material and injects heated welding rod into the joint. Polyethylene can be thermoformed and vacuum formed.
Experimentation is required to achieve the correct balance of material thickness, heat and timing.
Thermoforming can also be achieved with a 2-part mold, where both surfaces of the heated material are pressed between two molds and allowed to cool. Many of the above listed adhesives will work including auto body putty. A minor scratch can often be repaired by simply rubbing the scratch with a spoon. A large scratch or gouge is best repaired with a plastic welder and then sanding and buffing the repaired area to match the surrounding area. If welding is not practical, mars can be repaired with epoxy glue.