what do the freaking autobody shop use to cover their customer's car doors? i tried putting on the fender on my car and i scratched the door deep! and about an inch and a half long. you could even see the gray part! i was so pisst at myself.

nothing, you need to slow down and look at what your doing, you just dont go slapping a fender on.

tape

This might be the case with someone that has a lot of experience, but even the added insurance wouldn't hurt.

Yes yes, tape it up, blue painters tape works wonders, cheap insurance.