clay sand straw (and some water) smoosh it all together stir it up eventually you will end up with a pile of cob like this Tractor Cob -a much faster method of mixing cob than by foot -roughly 3 buckets of clay, 2 buckets of sand, 1/2 bale of straw -spread out each ingredient and run over it thoroughly before mixing with the bucket -add the hay after the dry ingredients are combined, cover the pile completely -soak the whole mixture down with the water hose -tractor cob must be mixed wetter than by foot, it may need to dry out before use -larger, more heavy duty forms must be used with tractor cob as so much weight will be on them scraping out the tractor cob spreading out the cob watching :) the heavy duty braces for the tractor cob wall That's our instructor, Diane, climbing in the frames to stomp the cob! The second day of the workshop, after we learned to mix the cob by foot, we learned how to make it with the trac...