Step 1: Tools and Materials
-Box cutter / razor blade
-A cutting mat (so you don't gouge your table)
-Hot glue gun and extra glue sticks
-A compass (the kind used to draw circles)
-Hole punch (apparently this can be used to punch the holes for the washers and such. (thanks to swhitaker2 for discovering this))
-Two new pencils
Step 2: Making the Rotors
1) Cut out three circles that are each four inches across.
2) Poke a hole in the center of each circle with the pointy end of the compass, the do the same with the pencil.
3) Draw and cut out a notch in each rotor about 1/2 in. wide at the top. Make sure you don't cut all the way to the center, but at least one inch deep.
4) Cut out two tabs that are 3/4 by 3/4 in. Then cut one tab that is 1 and 3/4 inches by 3/4 in. Scraps of cardboard are good for these kind of parts.
5) Make a cut-out in one of the rotors, about 3/4 inch deep and 1/8 inch wide, or however thick your cardboard is.
6) Attach the tabs to the rotors using hot glue as shown in the picture. Don't copy my layout exactly otherwise the combinations will be identical. Also be sure to arrange the notches so that they're all facing the same direction when you attack the tabs.