When I coded my Type-IV I first removed the screw, then hand-milled the wells on either side of the hole; put the screw back and filled everything with black paint. It looks like a single black rectangle, but it works. What I learned is you don't need to mill wells for the white codes, only the black ones, and wherever there are 2 black ones next to each other it can be one double-sized well. The wells also don't have to look exactly like the factory ones, mine are more elongated due to the type of tooling I used. Simplifies things a lot if you aren't married to the idea of making it look like factory coding. To me the point is to get the camera to recognize the lens properly, period. Marking the lens flange for coding is also quite easy without any device. A pencil mark on the side of the body flange corresponding to the ends of the reader window are easily then transcribed onto the lens flange edge, and then lines drawn to the inside of the flange. A third line halfway between them, then divide those 2 halves into thirds with additional pencil lines. All that's left is to mill an oblong well in whichever "pie sections" require a black code.
