Having understood the principle of the simple Elna discs, we made a disc with a simple wave pattern.
The disc has a minimum on one side and a maximum on the other. Over the course of the 18 stitches — at stitch width 4 — the machine therefore uses the maximum stitch width in full during one revolution.
More about the project can be found in an earlier blog post, Making ELNA Supermatic pattern discs yourself.