These raw castings are made from high quality gray cast iron. Made right here in the USA, cast in small batches by Clarke Easterling of Windy Hill Foundry. The 6x6x3 Machinist Blocks are great projects to machine your own fixturing square to whatever tolerance you desire. These blocks are raw castings, but if you’d like yours machined please reach out. We will be offering machined, surface ground, and scraped versions in the future.