This video will show you how to make motor casings. You'll need parallel wound paper tubes ¾ inch outside diameter, ½ inch inside diameter. You can make the same thing out of poster board and glue. In this video shows how to use the store bought ones. Use bentonite clay which is volcanic ash which is like a fine powder that when compressed down it becomes hard. This way you don't need to wet and wait for it to . Add 1 ¼ clay and then ¾ increments, dump into tube and pound it down with a rubber hammer really hard. Add your increments and pound those down too.