Neither. I used a pin and punched about a zillion holes in the edges of the belly pan. Put in place on the wing, drew lines.... put a FEW pin holes here and there, but most of it was where I had my CF weave epoxied to the wing anyway. SO I just sanded that to roughen it, used thick CA, put 'er on there...she's stuck fer GOOD.... NO signs of loosening, and remember I did all of my tunnel making/cutting/carving with it glued on the wing.