Mechanical Watch: Exploded View

I’m sure you have though about it already, but if you had a way to modify the refractive index of the resin, you could make the fishing lines disappear completely.

I never gave that any serious thought. What additives would do that, do you think?

Edit: A quick search reveals that there is quite a lot of prior art from the optical community. Darn, maybe I'm not done here.