Knuckle bones, also known as Shagai to the Mongolians, Astrogaloi to the ancient Greeks, and Tali to the Romans, were made from the knuckle bones of hooved animals and were used for games of chance, skill, and divination. This oldest known form of dice was played all accross the ancient world, in medieval Europe, and is still played in parts of central Asia.
HOW TO PLAY:
There are as many ways to play as there were cultures that used them. The basic concept is the same throughout. Each bone can land on one of four unique sides, with unequal probability. Print four copies for Roman rules, more or less as needed for other games. See this article on Roman Board Games for the Roman rules. For a comprehensive history and rules of many games played with knucklebones, see the Wikipedia entry. This paper by Jenna Mortensen is a great summary of how these bones were used for divination.
Images are of a strong and flexible laser sintered version, which feels and bounces just like real bone. Video description here: https://youtu.be/I7cBvwAvyIo Available from my Shapeways store: http://shpws.me/Kd2v
The bone model is a 3D scan of a real sheep tali which I ordered from a fur and bone store and had to figure out how to clean, bleach, and preserve.