HI I USE A METAL YARD STICK ON A PIECE OF PLEXIGLASSTHE YARDSTICK IS HEAVY IN METAL AND THE PLEXIGLASS HOLD THE FILM FROM MOVING WHEN YOU MAKE THE CUTS -WITH A SINGLE EDGE RAZOR BLADE- 3/8 SEAMS CAN BE JOINED BEFORE THE FILM IS ATTACHED TO THE AIRFRAMEWORKS VERY GOOD OVER OPEN WING BAYS-IF USING ONE LAYER OF FILM WITH A FEW DIFFERENT COLORS-I ALWAYS OVERLAP THE TOP WING FILM OVER THE BOTTOM AT THE LE AND TE TO KEEP THE JOINTS STRONG AND PREVENT FUEL FROM GETTING UNDER THEMA LIGHT COAT OF SIG BUTERATE CLEAR DOPE CAN SEAL ANY DECALS OR SEAMS THAT MIGHT BE EXPOSED TO FUEL-IT CANNOT BE SEEN WHEN IT DRYS-CAN SPOT FUEL PROOF UNDER THE FILM WERE THE MUFFLER WILL SPRAY HOT FUEL TO KEEP THE FILM ON FOR THE LONG TERM-ENJOY TONY