I forgot to add a little "How To" on wheel arches...This used to give me fits when I first started doing these things... 
First, you'll need the stuff found in this first picture..A template, box cutters, and a pencil...I found these box cutters to be awesome at this...Then, you'll need to mark out where the arches are gonna be with a template or something, of course....Once you've done that, you just cut a chunk of the plastic out of the middle of the arch...This will allow the plastic to separate a lot easier while you're cutting; thereby making a cleaner cut...Trust me, it works a lot better than I can explain...Then lightly score on the line you've marked out...Make sure you do this, as it will make subsequent cuts much easier...Then just keep scoring until the plastic separates..Use just the very tip of the knife so you can maneuver on the line...It takes a steady hand, but if you go slowly on the first scoring it will provide a grove that will make cutting progressively easier....Suddenly, you have a nice clean wheel arch...
I'm sure there are more refined methods of doing this, but if you don't have a lot of money for laser cutters and such, like me, then I'd recommend you give this a try...
Only took me about five minutes to do; including photographing it...
I hope this provides help for somebody, as I really needed something like this when I first started, but couldn't find anything...
Edited by kilrathy10, 05 December 2012 - 06:38 AM.