Hi, I'm in the process of building a fur tumbler (5.5 feet diameter) for my own tanning use. (Only small games I trap, like beaver, otter, coyote, fox, mink, muskrat, fisher etc.) I'm building a closed tumbler (with media), and I wonder if I really need an "open" one as well, like the ones that have wire mesh instead of plywoods. Is it only to clean hides from the dust, and if so, is there another way to do it ? And for the media, how often will I need to change the saw dust ? (There's no grit where I'm from). I was thinking adding golf ball with the saw dust, wath do you guys think ? Thanks in advance, really appreciated.