http://www.telescope.com/catalog/search.cmd?form_state=searchForm&keyword=focus+wheelsFocus wheels could be used for cool looking volume control knobs. They're on sale right now.
However, I don't know the shaft diameter will fit. It looks close to being right.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.telescope.com%2FOrion-Classic-Brass-Set-of-Focus-Wheels%2Fp%2F7322.uts%3Fkeyword%3Dfocus%2520wheels&hash=4fcff2d500c7056b7678bf511e683c4f97460afa)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.telescope.com%2FSet-of-Orion-Sport-Aluminum-Focus-Wheels%2Fp%2F7323.uts%3Fkeyword%3Dfocus%2520wheels&hash=631c191ea6a353dca1015269643fc7cde14f6a58)
