So I'm trying to paint my bumpers and side skirts black this weekend. I got rear ended not too long ago and there is a gouge maybe 3 inches long on the corner of my rear bumper. I was wondering what I had to use to fix that since it is ABS.

 

Goto your auto paint supply store, they should sell a special filler that is flexible for plastics.

 

Also maybe pick up some gauze backing tape, or even aluminum tape. You may also be able to find a plastic welder for cheap. Basically what you do is remove your bumper, slightly V the gouge, put your backing tape on the inside of the bumper, lay the plastic you are going to be welding into the gouge, weld the plastic in, let it dry, DA it down, primer filler, wet sand, seal, BC/CC. Or if you are going to just buy plastic repair material, use the same steps only with the plastic repair material you mix it up just like bondo/plastic filler (with a hardner).