Fiberglass? Anyone use it?

[dabears]

I did some searching on here as well as google. Google gave answers as to how to use fiberglass i kinda get it but my question is has anyone here used it to remake their parts? The fenders i am making are too think being make from a 4"pvc pipe.. i could thin them out by hand but then i got to thinking why not just make them in fiberglass? For bigger applications i can see it being easy, but for casting fenders has anyone done it? How hard was it to do? From googleing around i saw its easier to do from a mold or reversed copy of what you want to make.. So would i just use the fenders i made to make a "mold"? I like the idea of using fiberglass 1 for strength but 2 for the thickness being smaller. I was at lowes today and fiberglass meterials are not all that expensive, but i dont want to ruin my originals in the trail and error process?? Anyone have any ideas, tricks, hints??