Are you talking about the boots or bungee covers? my wife made some for me out of thin nylon with drawstrings. I also used small o-rings to hold them where I wanted them and help hold the drawstings inside. A Website called the Cub Den has them available for purchase too, like 10 bucks a set I think, hope I helped... the open triangle section can be filled with light balsa using CA and then sand it smooth with the tubes, if you are using fabric you might be able to just make it stick to the tubes too, but Monokote probably needs the balsa to stick to, worked well for me anyway.