Bondo...it's all in the mix. You don't have to get crazy and weigh it out unless you're ocd, but measure the components carefully and mix thoroughly. Helps to knock down the high areas on the scrape with some 80 grit. Spread it into the scrape with a putty knife or whatever. Let cure completely, then sand, prime, shadow, sand...rinse, repeat.... then when you can't tell where the repair was with it primered, sand and primer and primer again and then paint.