Invented by French farmer Jean Pain in the 1970s, it is made of woodchips and sawdust, surrounded by a ring of hay bales for structure and insulation. As the Pain Mound decomposes, heat is produced and harnessed using a hydronic loop. The Pain Mound will produce heat for up to 18 months, after which time the remains (nutrient rich, earthy humus) can be used to build soil.
Stake out a circle approximately 12 feet in diameter. Purchase hay bales from a local farm, collect fallen trees and branches, and rent a chipper. A load of sawdust can usually be procured from a local sawmill: they will often deliver for a nominal fee.