I'm a big fan of Joshua Silver's adjustable liquid-filled eyeglasses. It's simple concept, great design, and has the potential to have a huge impact. If you agree, I recommend supporting them. What's the point of having factories that can mass produce nearly anything, if we don't utilize those capabilities to solve legitimate problems.
Since I first heard about them, I've always wanted to create an adjustable water lens. I don't have any specific goal in doing it, it's just an open-ended ambition. While glasses are probably the best use for this technology, I feel that like it can be utilized in various other ways. At a bare minimum, it will be a fun toy to play around with.
The first prototype works better than I anticipated. It consists of two printed parts to hold everything together, two pieces of clear acrylic used as lens covers, two silicone o-rings with a square profile, and a flexible clear membrane that cut out from shrink wrap packing that I had laying around.
By injecting water with a syringe into one side of the lens, I'm able to adjust it from being plano-convex to plano-concave. The film I'm using isn't ideal and tarnishes the clarity. The acrylic also has some surface scratches as well. It's pretty fun to play around with.