I use left over lead tire balance weights from service stations. For adding weight to the rear of the fuselage I first find out how much weight it needs to balance. Then I smear canopy glue on the weights and drop them into the rear of the fuselage one at a time and then keep the plane pointing up overnight until the canopy glue sets up. In the morning point the nose down and shake the plane to make sure that the weights have been glued solid and won't come loose. IF they stay put then your set!!