I have a round tuit you can borrow.I've got the attachment for my mixer, and made them before. I wasn't very happy with the casings I had - too thick, the recipe - missing something, but couldn't say exactly what, and the texture was too coarse.
I can fix the casings by buying different ones, and the texture by double or triple grinding. I might try again, and get the recipe for Cumberlands - hadn't thought of doing Cumberlands.
Just need some round tuits, and we're good