In March of this year I received an email from Nebojsa Ilijevic. He is a blacksmith in Belgrade, Serbia and he was seeking some technical information about my tumbler. He had seen it on the web and was thinking about building one for his shop.
I answered his questions and thought that I would inquire later to see how his project turned out. However, I got busy and forgot about that until just a few days ago. I wrote to him and he kindly replied with some images of the machine he built.
His tumbler is longer than mine and uses an interesting triple belt system to drive the rotation. I looks like it will take some time to remove the rust from the interior. Nebojsa was quick to point out how much loud noise the operation produces.
Check out his website - the wrought iron button leads to a nice gallery of work.