i made some rear "valences" the other day... aka carefully trimmed some factory mudflaps and painted them to match the body color. they really help fill in that naked rear wheel well area.
trimmed the flap with an air-powered cutoff wheel and smoothed/rounded the edges with a file. masked off the flap edge and sprayed the actual "valence" part. let dry, remove masking, and install. pretty easy stuff.
before and after trim:
trimmed, cleaned, masked and sprayed:
installed:
