I once saw a project in a community garden were old water tanks(?) or a similar drum were used and simply put on the ground. doesn't it make more sense laying a drum on the ground (maybe not the size of an old water tank and give it some kicks every day? which size is ideal for a tumbler? And does it makes sense at all since it has no soil contact?
In my case, the tumbler is necessary because it can sit on concrete without making a mess, and it completely hides any evidence of composting from my neighbors. Otherwise, keep looking.
Honor Bateman wrote: The "tumbling" supposedly helps you to turn the pile more easily, but it's a joke. When you turn the (full) tumbler, everything inside sticks together in one big lump and just flops over onto the other side. There is very little mixing going on.
X2. I've tried composting in different containers, but its hard to turn it properly. A loosely covered pile on the ground that can be turned inside out and top to bottom with a pitchfork or similar is the way to go, IMHO.