A good way to cut a clean gasket is place gasket material over the part if you have room ..then tap around with a small ball peen hammer..then use a pipe ferrel close to the screw or bolt size to cut the hole openings..if you cant keep the naterial in place tap and cut a couple of holes oposite each other and screw the material to the part to hold it in place then tap out your impression ..some times you can cut the gasket completly out by tapping it but sometimes use a scissors to follow the impression ...some may already know this and some might not..it has worked well for me for a lot of years