Old telephone books and copies of MA make good weights for holding down the sheeting. I prefer to wet the sheet then lay it on the wing with no glue, and then weigh it down. to dry in place. Next I use CA glue to attach to the leading edge, wet the sheeting again and then use wood glue on the ribs until the last inch on the trailing edge where I use Med CA again. I have also made weight bags using QT size freezer bags filled with sand and enough water added to make the sand moist. The water keeps the sand from slipping down to one end of the bag and allows it to be molded around things. All kinds of ways to do it.