Our feedstock of choice is forestry waste from the Melina mill, just a stone's throw from the shop. Melina (Gmelina arborea) is a fast-growing tropical hardwood native to Asia, related to Teak, that's widely used as a utility timber (pallets, plywood, construction lumber, millwork, even furniture making). Our local mill cranks out pallet pieces which get carted off and assembled elsewhere. The waste comprises "flitches" (semi-rounds from squaring up the logs), trim scrap (mostly in the 2cm by 5-10cm range), and sawdust. We're focused first on the trim scrap, because of its abundance and the fact that it's easy to handle and dries relatively quickly.
Melina is widely grown in vast monoculture plantations and harvested after only 10-12 years. In our area it is cut into roughly 2M logs, dragged out by oxen, and loaded onto flatbeds. There are several Melina mills on the Osa, at least two in the greater Puerto Jimenez area (where our shop is). Once cut, the stumps sprout multiple shoots, and seedlings also sprout from the newly sunlit soil. If plantation sites are not cleaned after harvest, a dense impenetrable Melina thicket will grow up through the trim slash with little prospect of commercial utility.