The material is 3/16" birch dowel available at the box stores, Hobby Lobby and many local hardware stores. Cut it to length and slightly round the tips. It is a pressure fit and can be made out of 3/16" deldrin or nylon rod. Do not use metal rod because it could ruin the finish in the hole. Elsewhere in the post "Buck rogers Rocketeer" a picture of a homemade unit is posted. Hope this helps.
Rodney