I use a piece of plywood cut 24x24. Cover with a layer of insulbrite that is cut about 23.5x 23.5 to avoid bulk on edges. Cut the silver iron fabric at 32 x 32. I hot glued cabinet cushion to plywood back. Then wrap the the silver fabric. I used straight pins to hold.
For a straight edge, I use a 48 inch metal carpenter ruler. No need to draw lines.