Hi, Most material can be used depending of a specific thing you want to test. They are sometime made of thin steel, other time they are made from fiberglass. Buster, the dummy in the TV show MythBusters have bones made from poplar wood and i find that a very good material. Animal bones (pig) could also be used. To make a bone more realistic from wood, one could hollow the middle fill it with foam and glue it back.