When I went to Granada with my good friend Pepe he showed me his hand-made macro lens. It was incredible the good quality and the huge macro than can be obtained with this technique. It requires a little bit of hand art skills and patience, but the results are really interesting:
Pepe taking a picture of a tiny piece of bread on the table.
As you can see in the picture, the lens is connected to the camera in the reverse sense. He took a body cover cap, removed the front part and leave only the Nikon F-mount part of it. Then he took a filter and after removing the crystal he attached the external ring to the previous modified plastic cover creating a single piece that can be attached to the camera body from one side and to the front of the lens from the other side.
As you can see in this picture the external part of the lens is the part that normally is inside the camera. Just the reverse!
Look at this 1 Euro cent coin with a Nikkor 24mm and see the next macro one using the same lens with the macro-technique.
This is a picture took by Pepe to the eyes of an insect.