shift 0
How to build it
- Print both PDF pages at 100% scale (no “fit to page”).
- Cut out both discs along the solid circles — plus the small window slot in the small disc.
- Place the small disc on the large one and push a split pin through both centre marks.
- Rotate the small disc to set the key — the window under the pointer shows the shift number.
- Encode: find each letter on the small disc, write the large-disc letter beside it. Decode: the reverse.