Yo,Martin-
Are they fiberglass or plastic? If they're FG, use a very fine bladed saw and go slowly when cutting them or they'll crack all to heck. Sometimes it helps to put masking tape on both sides where the cut is. (Added bonus, you can draw a big ol' black line on the tape where ya wanna cut!) You might want to give it an extra 1/4 inch or so and sand to a smooth edge after you cut.
Good luck with it, Bro!
_________________
JD, father of
Quinn, Son of a...
Build LogQuinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special "Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom