[Christ]

yes, you can fiberglass plastic. It's easier to cold weld it though. Well, not easier, but it works better. Well, not better, but it's still good.

Cold-welding ABS plastic:

1. Cut 1x1mm bits of ABS, without paint on them
2. Leave them dissolve in acetone (not nail polish remover, actual acetone)
3. After they've set for awhile, they become 'gooshy' and you can bond them together by kneading them
4. Roughen whatever area you want to apply the new plastic to, and stitch it together tightly with nylon thread (yes, you have to poke holes.
5. Make sure you roughen an area at least 2-3 inches away from the crack in all directions, removing paint and some material
6. Apply the new plastic and smooth it out, like bond-o, but apply more than you need, so the area is rough and higher than the surface you want it to match.
7. Leave it dry over night, and rough file it in the morning
8. Sand it smooth, prep, then paint.
9. This method also works to put new pieces on old bumpers. (change the shape/look)