[header] How to build a single tank biodiesel processor [title] Gather together the few common items listed under " things you'll need. [step] " [title] Assemble the drum. [substeps] Cut a large opening (about half the top) in the top of the steel drum. 
You may also be able to find a drum with the top already removed. Drill a 1.5-inch hole in the bottom of the drum.