As Kip has said, the problem has many solutions, the rubber band (make one from an old inner tube if you want to). A weight of any kind can be used to provide the weight necessary. I have a dob that has two diving weights simply screwed to the back end of the tube. You do want the weights close to the scope's axis as you do need to have a balance when the scope is pointing high as well as low and you may want to put a weight on the bottom side as well as the top side. Attachments to the end tend to balance well and you can just put so many pieces on to a short shaft on the backside or even into a pocket on the backside with a velcro cap. You're not going to turn the pocket upside down in operation so a small pocket to accept 1 lb. weights as necessary.