I use the approx 6" wide automotive stuff you can get in any automotive or big box store auto section. No idea what the weight is, but it is available, cheap, and it works. Wide enough to make the saddle under 'glass (don't try to eat that one) so you don't end up smunching balsa sheeting. Attach with a thing film of spray adhesive, then finish with epoxy. Spackle to fill.