shaving a plastic bumper

i have notice on a few frontiers they have got rid of the fender flares and smoothed out the front bumper to match. can anyone tell me how to do this

you cant melt it together or use plastic epoxy. fiberglass wont bond. it will at first but it will fall off

i just recently found out you can take shreds of ABS plastic & mix it with Acetone in a 2:1 ratio & it turns into goop similar to bondo. It can also be applied like bondo as well. Of course it's sandable as well