Ok. I have read the tutorials and all, so this is my verdict, and correction would be appreciated if I am wrong, but first I'll show you what I plan on doing.
I plan on mimicking every underbody spoiler mold found on the S55, and putting it on the S500. Basically im transforming my S500 into an S55, from back to side, to front moldings and underbody work.



So I buy styrene, expoxy putty, and epoxy glue. On top of that, plastic spray paint and polish.
So I remove the fender from the car, cut pieces of styrene too mmy liking and size preference after epoxy gluing them onto the fender, then use a dremmel tool to smoothen them out, and maybe sand paper. Then use the epoxy putty to smoothen where the styrene borders the actual part, then more smooting, then paint and stuff..........something like that?
Like this, then smoothen it out?