Though I haven't seen one of these hacks in person for the MJ's, the relative costs for construction compared to the falling price of the seio line of pumps makes them a lot more attractive and one less thing to have to worry about. The Seio M2600's are flooding the streets now, so the smaller 620 and 820's prices are dropping. The M620's are running around $30 or so, might be a better choice unless you happen to have the props and such hanging around and want to play.