This is a very simple pallet compost bin plan, which can be cheaply built out of used pallets. Make sure the pallets are not made out of pressure treated wood.
That’s it, a simple two step process to build a pallet compost bin. You can also incorporate a 5th pallet as the floor of the bin, which will help with air flow and speed the composting process. If you live in a dry climate it is good to line the bin with plastic to help it hold moisture. If you live in a cold (snowy) or rainy climate cover the bin with a tarp to maintain the proper level of moisture.