I had a bodyman do it for me... he's excellent with that. I have absolutely no body skills...
My car is all professionally done. I decided not to do anything myself after I ran into my first home mechanical issue. I don't want the headache of guessing what idiot thing I did that is causing the car to not run properly... lol. This is beyond my scope of personal skills.. im more a computer type guy now... haven't done any true mechanical work for about 20 years... (other than maintenance/brakes, etc..)
I'm lucky because Reg Reimer lives in my city.. so that's who is doing my car mechanically. Bodywise, the guy I have doing all the body/paint is a very OCD personality when it comes to the tiny things (as long as he's not rushed). He took about 4 months to do my car originally because he kept finding small things to touch up prior to paint. Those rear bumper add-ons have been on for almost 3 years now and show no sign of cracks or anything so they are put on really well. I do know its a autobody putty or glue used to make it look stock, not fiberglass.