I'd expect that just putting the lens on top of a pinhole would just soften the image a bit, I think the trick is to open the pinhole up a bit. Regarding epoxy, it shouldn't shrink on trying much at all. The Duco-branded glue you are using......is it two or one part?
Originally Posted by holmburgers
Anyway, the shape of the lens you create will depend on the surface energy difference of the two surfaces. In other words, how much does the glue wet the surface of the base material. If the base is, say, teflon, it will tend to stay more spherical. The other approach to change the focal length (and shape to a lesser extent) is to simply make a much larger drop. I think this is probably the best bet. I suspect the easiest way would be to form the drops on a sheet of polyethylene, maybe coated with oil, then pop them off and put it onto your pinhole.
I've spent a ton of time at work lately working with very similar things. Also, remember that your drop will not be all that close to a true sphere. In zero-g it would be but stuck here on earth, it will be a flattened sphere....I really son't think that will matter for what you are trying to do except to add more cool distortion!