THERE ARE ALOT OF HANDY TOOLS FOR DUCT BOARD A GOOD TOOL FOR MAKING ELBOWS 45'S AND OFFSETS IS SOLD IN MOST SUPPLY HOUSES. IT IS AN ALUMINUM PIECE OF METAL WELDED TO A 15 DEGREE AND A 22 DEGREE ANGLE. THE NAME ESCAPES ME RIGHT NOW BUT i'LL ASK OUR DUCT MAN AND GET BACK TO YOU.