Hey guys, We need someone to build a quick and cheap vacuum chamber capable of curing at least three 8 inch diameter x 5 inch tall high fuel grains at once for the Mk IV. We can use a pump something like this http://www.amazon.com/Robinair-15310-VacuMaster-Single-Stage/dp/B005CO9GX6/ref=sr_1_3?ie=UTF8&qid=1389667553&sr=8-3&keywords=vacuum+pump#productDetails we just need the actual chamber to contain the vacuum. There's a lot of do it yourself type plans on the internet. It could be three separate chambers if that makes things easier. Who's interested? Best, Armor -- David Armor Harris Boston University Rocket Propulsion Group davidh@xxxxxx