Such contraptions are known as, unsurprisingly, rotary rock tumblers. But what [Fraens] has put together here is a vibratory tumbler, which…well, it vibrates. If this was Rockaday we might go ...

Such contraptions are known as, unsurprisingly, rotary rock tumblers. But what [Fraens] has put together here is a vibratory tumbler, which…well, it vibrates. If this was Rockaday we might go ...