I have a little trick I use on sheeting I use you may find of interest. I save up old phone books and use them to weight down the wing sheeting. They don't cost me anything and they are form fitting. Some guys I know use lead/steel shot but if the bag leaks it can be a mess. Also if the paper sticks to the wood due to some stray glue or is damaged you can pull the damaged sheets off and anything on the airplanes sands right off. Since they are one place the pressure is equal so no sagging with thin sheeting.