I tie a lot of flies with barbell eyes, but frankly have been getting away from lead eyes because they break. If a mold was made, I would like to see something with a wire insert for reinforcing the cross bar, that would be a much better design IMO if it can be done. I know that would make the eyes more costly, but I'll take that over spending time tying, to have the barbell break and the eyes fall off. I epoxy over a lot of the eyes on flies and they still break & fall off. It's frustrating.
I'm using brass eyes more now, and they're not cheap to buy, so there should be a trade-off to the cost.
I've considered having a mold made, but can't get past this breakage problem and am not sure the best way to fix it.