How to Make a Code Wheel

You need two concentric circles (one circle should be larger than the other). Punch a hole in the middle of both and attach with a brass fastener so the top wheel (the smaller one) can move independent of the bottom wheel.

Drawing over the entire circle, divide into 26 sections. Use a protractor to get each segment the same size -- they should be about 13.8 degrees each

Write the letters of the alphabet, in order, on both circles.

To use, determine a number to use a cipher, for example: 4.

Turn the inner wheel that number of turns (so A >> E, B >> F, etc). When writing the letter, look at the inner wheel and write down the letter that is matched on the outer wheel.

For additional complexity, use a cipher that changes on each letter (such as the digits of π or the numerical digits of a sentence).