Depending on the thickness and/or strength of patch needed dictated how many layers of mat I used. This patch I used 7 layers of material, lay them on a large piece of glass or cover plywood with foil. glass works better as it's very smooth and easier removed. Cut all layer to size, square them up in a stack, mix resin and pour mixture in between the layers. It will get messy quick. After thoroughly saturated, lay a sheet of aluminum foil over it and begin to work from the center out, squeezing all the humps of liquid you feel or see out to the edges. Once you feel that you have it worked down as tight as possible, get a heavy pipe or something smooth and round, again roll from the center out then start rolling in one direction or another but roll in continuous motion from one side the the next. do this until you get it flat and tight as possible. Let stand to cure, if you remove the foil to quickly it will pull the layers apart. You'll feel the patch get hot when it is curing. Someone also said you use wax paper but I have not tried it.