What I did..
On my -4, I made a simple wood mold that mimicked the rib shape and depth. I took my completed elevator, minus the weight and set up on balance point, then filled baggie with lead shot and taped to rib tip, adjusting amount until slightly nose heavy (compensate for paint). I then melted and poured into wood mold. After cooling, drilled and counter-bored for mounting bolt through rib. Test fit with bolt/nut while in balance jig to obtain slight nose heavy condition. I then primed the lead weight (rib already primed, and installed the weight with Proseal to completely water seal the weight in the rib. The finished product looks almost molded in, and was painted during final paint. In the event it would still balance nose heavy, it is possible to drill a hole to remove weigh, then touch up paint. I do not like the idea of a bonded or glued weight, because if it comes loose, your elevator will likely jam, and obviously, you risk flutter with loss of balance, hence, mine are bolted and sealed in place. The whole process from mold making to installed took an afternoon at best.
8A7 / Advance NC