Once I read about extracting the resin from leaves by wrapping a big bundle of leaves in cheese cloth and then soaking it in a bucket (or barrel) with gallons and gallons of acetone. The acetone removes the resin then you need to let the acetone evaporate, which takes a long time, but you end up with sticky black tar in the bottom of the bucket, that you are supposed to smoke. However I could never bring myself to smoke that ugly looking shit and I just threw it away. I prefer buds.