I dug out my old Soligor 400mm f5.6 lens with OM mount. The aperture stopped working long ago, and the lens never was that good to begin with. I disassembled it and started playing with the elements. I discovered that if I removed the rear group, and left the front group in place, it made a pretty decent macro lens. Of course, it looks quite silly, but mostly works. This is the front bezel, taken from a distance of about 2.5 feet. The coin is a US Dime. It would probably be sharper if I cleaned the fingerprints off the elements. And this is what it looks like on the camera, with all the leftover bits.