Ball lenses in their complete form have a long tradition of manufacturing and use. They are also a good starting point for making other lens types that would otherwise be tricky to make. For example, flattening and polishing one side of the sphere result in the general plano-convex, half ball, or aplanatic lens depending on its central thickness. For the half ball lens, that thickness is D/2 and D/2+D/2n for the aplanatic lens. By further simple transformations of these lenses, it is possible to get the drum or the rectangular shape of these lenses.