This is a replica of the M-94 cipher device with accurate dimensions.
See http://maritime.org/tech/csp488.htm for more information about the M-94 (also known as CSP 488).

Each of the wheels can be fabricated with original alphabet orderings by creating an scad file like so:

use REPLICA = false; scale([2, 2, 2]) wheel(17);

There are 25 wheels, 1 .. 25, in the full set. Setting REPLICA to false makes a 3-D printable object. I am still in the process of refining the printable models to reduce the amount of time to print and achieving best readability of the letters.

You can download a full set of 3D printable wheels (STL format) from all-wheels.zip.

Source code on GitHub.