One way to have cheap fisheye lens is to use “Door Peephole Viewers”. These plastic peephole viewers are avaiable around 5$, so you can mount these lens before your camera to have a ultra wide angle effects. http://aggregate.org/DIT/peepfish/
New Liquid Lens Digital Camera Tech
The lens consists of two immiscible (non-mixing) fluids of different refractive index (optical properties), one an electrically conducting aqueous solution and the other an electrically non-conducting oil, contained in a short tube with transparent end caps. The internal surfaces of the tube wall and one of its end caps are coated with a hydrophobic (water-repellent) coating that causes the aqueous solution to form itself into a hemispherical mass at the opposite end of the tube, where it acts as a spherically curved lens.
The shape of the lens is adjusted by applying an electric field across the hydrophobic coating such that it becomes less hydrophobic – a process called ‘electrowetting’ that results from an electrically induced change in surface-tension. As a result of this change in surface-tension the aqueous solution begins to wet the sidewalls of the tube, altering the radius of curvature of the meniscus between the two fluids and hence the focal length of the lens. By increasing the applied electric field the surface of the initially convex lens can be made completely flat (no lens effect) or even concave. As a result it is possible to implement lenses that transition smoothly from being convergent to divergent and back again.
If you want to reproduce the results of coded aperture, or color-filtered aperture, you need to disassemble a lens to put in some masks. There are some documents you need to have before you start to do it,