I drilled a hole in the wingtip with bit the same diameter as the weight that I used(I used 3/8" brass rod). Then just gorrilla glue it in. When it dries, just put a patch of Ultracote on it and you cant even tell it's there. BTW it made a world of difference on my Extra Special. Before adding the weight, it would fall to the right every time that i popped it up. Now its dead straight.
Brian