A cipher disc is made up of two (or more) circles that are concentric and of slightly different sizes. These circles are inscribed with alphabets that move relative to each other in order to encipher text. Ecozcelik has made comprehensive instructables on the Caesar Shift and Vigenère Cipher, both of which are commonly utilized with a cipher disc.
This instructable is meant to be pretty simple, but you can make a really cool disc by following H2Powerman's instructable.
Step 1: Materials
- Protractor, Straightedge, Compass
- A cheap drafting set can be as low as a couple dollars but a more robust set may be much more.
- Frequently sold at a couple dollars per dozen. (If properly sharpened add a sharpener to this list)
- Thermal Laminator
- These tend to run from twenty to two hundred dollars. Expect to pay thirty to forty dollars.
- Thermal Lamination Sheets
- These often come in large packages, but you should not expect to pay much more than a dollar per sheet.
- Also known as "paper fasteners", a dollar or two should result in more than enough.
- Printer Paper
- Very cheap.
- Prices and styles vary but anything around two to ten dollar will probably suit you just fine.
Please note that many of the items listed are optional. while I recommend a drafting set, online template, or software in order to assure accuracy they are not strictly necessary. Likewise laminating protects and cleans up the product but can be substituted by using sturdier materials or a disposable design.
Step 2: Draw the Circle(s)
This circle represents one of your discs (in my case the outer disc) make sure you leave room around, inside, or next to this disc for another differently sized disc. Your discs must either never overlap or be concentric. Concentric allows you to measure once by using a photocopier, while separate circles surpass the photocopier by measuring two discs. Size may also be a consideration and you can make your circles on separate pieces of paper.
If you intend to use a protractor in the following step I recommend making any circle you have to measure individually about the same size as your protractor.
Step 3: Measure Divisions
Draw a line through the center of your disc that intersects the perimeter on either side. Using the bisector as a starting point measure the divisions of your disc, I will be using the English alphabet so I want twenty-six divisions. Three hundred sixty degrees divided by twenty six letters should result in lines 13.8461538462 degrees apart (according to google). I used a protractor to accomplish this but any mistakes tend to become apparent later in the process so I implore you to be precise.
Step 4: Complete Template
To do this I simply made smaller circles within the original and then made liberal use of the photocopier. However, if you want to do away with technology you are welcome to repeat the previous steps on a smaller or bigger scale in order to make the additional discs. As an alternative to the preceding steps you can download an online template.
This is also the time to fill in your alphabet. All of mine are in alphabetical order for use with Caesar Shifts and Vigenère Ciphers, but you can mix the letters up to make things interesting.
Step 5: Personalize
This step is completely up to you but here are some ideas:
- Making a cipher disc into a color wheel allows you to leave secrets in coloring pages (a form of steganography)
- Multiple discs allow different symbols and can rotate independently for poly-alphabetic ciphers
- You can write clues on the back of the disc before or after lamination, be sure your message does not bleed through or wipe off
- You can superglue a jewel or googly eye to the brad
- Glue another paper to the largest circle to sandwich a secret or add fancy trim
Consider why you are making this:
- An escape room may benefit from a grayed out design with additional discs for multiple puzzles
- Bright colors work great for Easter egg hunts
- An un-laminated print out template is accurate and disposable for passing notes in class
I am not liable for any debt you incur buying googly eyes.
Step 6: Laminating and Final Touches
Once you have your template cut out your discs and laminate them. Follow any common sense associated with your laminator, do not let anything overlap, and keep the sheets properly aligned. Next cut out the discs from the plastic. Be sure to leave a border of laminated material in order to sustain the seal.
In order to install the brads and bind the discs into a singular whole I used a knife to make a semicircular incision. This cut should be big enough for the brad to get into without slipping entirely through.
Step 7: Thank You
I am far from the first to make a Caesar Cipher (or write an instructable on it), but I hope I introduced some new ideas to someone.