Juice,
get thee 3/4 oz of BBs or split shot. Drill a small hole in the wing tip slightly larger than the weights. Coat each piece with epoxy and drop through hole with wing vertical so BB or shot falls to trailing edge. Add some additional epoxy for insurance and allow to cure. Shake it good tomorrow to insure nothing is loose. Check balance and seal the hole. Subtract a BB or two to compensate for epoxy.