Cup Cryptex
A cryptex is a device that contains a sequence of cylinders with letters on them. The cylinders are rotated to form words and unlock the device.
Don’t happen to have a cryptex lying around your house? No problem. You can easily fabricate one with a few Styrofoam cups. The point of using Styrofoam cups is to use some that have thick lips so that when they are stacked, a region of the cup is still visible.
The cup cryptex is created by writing letters around the lips of the cups. The letters should be spaced evenly around the lip. When the cups are stacked (in the correct order), the cups can be rotated to form words.
A typical cryptex device will unlock and open with the correct code. A cup cryptex will obviously not do that. Instead, the players will arrange the letters to form a key word presented to them, and elsewhere that arrangement will show the code word(s) they need.
A cryptex often has 26 letters on each cylinder. Your cup cryptex does not need that. Instead, you will probably have 4 to 6 letters per cup/cylinder. When arranged correctly, each row will form a word.
You may or may not provide the order in which the cups should be stacked. If the order is not provided, make sure that there is enough context to reasonably figure out the order based on the words formed.