A piece of chicken wire and four wooden stick. We made about two and half feet in diameter. After that, you can pile in anything you want, grass cutting, tree leaf, fruit peels, etc. Just remember to put some soil every time you add anything to the pile. And it is best you have some brown material for the compost. Also, try cover the top so that rain water doesn't get in.
After couple of days of constructing the pile, it was so hot that you can hardly touch it. By the beginning of this spring, we spread the pile on top of our veg. garden. I think that improved the soil a lot.
But you can also buy ready-made ones from different places. The chicken wire one is probably the cheapest though. The fancy ones will cost over hundreds. Also, you can build wooden boxes if you have a big enough space in your back yard.
We are thinking of starting a worm bin in the winter. Anyone tried it yet?