Believe it or not sign language can be an effective way of communicating a numeric code, clue, or short message in your Escape Room. Sign language by definition is a visual form of communication. Some of the more intricate and complication hand movements/gestures do not translate well to medium such as engraved wood, but the basic alphabet and digits 0-9 certainly do.
Each letter of the alphabet and single digit can be expressed by a single hand. Letters Z and J involve movement, but this is easily conveyed via arrows indicating the motion involved.
See the image below to see how the alphabet and 0-9 are represented in sign language:
Can you envision different methods of implementing this in your Escape Room?
One method we devised is through the use of a panel displaying the different configurations. We came up the aptly titled "Sign Language Panel."
Do you know what this says or do you need a bit of help?
One of the great things about using sign language is the creative ways you can assist your escape room participants in decoding the message. For example: Perhaps you have the symbol for "H" (the leftmost in the image above) pointing to a book whose title begins with the letter H. If you are using it to relay a numeric code you could have 7 notches below the symbol for 7 somewhere in the escape room. These ideas are rather basic, but hopefully they jump start some of your own.