I'm currently making my grills for the same GRP clam, and it really isn't bad at all. I found that scoring the mesh with a dremel cutoff tool makes it very easy to cut an arc, and I also use "trauma shears" for larger straight cuts. For ends, just find something lying around your garage that has the radius you want to bend - use a tube or a 2x4 depending on what kind of bend you want. It only gets tricky when you want to have a compound bend, but single bends are trivial.
I also suggest doing all this before painting and primer in case you scrape anything.
"Lots Of Trouble; Usually Serious"