But even still, this largely 3D printed rock tumbler from [Fraens ... you could always take the easy way out and make a rotary tumbler out of an empty tomato sauce jar and a scrap motor.

But even still, this largely 3D printed rock tumbler from [Fraens] is unique enough ... Such contraptions are known as, unsurprisingly, rotary rock tumblers. But what [Fraens] has put together ...