I've tried them with little success. Making them takes little time:
Use a badnsaw with a guide or a table saw to rip out 1/2" squares a few inches longer than your draw out of a board or split of a tree (like hickory, spruce, cedar, etc.).
Chuck these up in a good electrical drill with a good bit of power in it.
The run them trhough a piece of metal with several graduated holes from 1/2" down to 3/8". Then sand it.
Takes about half an hour to make up six to twelve shafts from a soft board like pine, longer for hardwoods and tree pieces.