http://www.brewboard.com/index.php?showtopic=53801&hl=stirplate&st=0
This is the one I used to make mine. Just got a Erl. flask and stir bar in yesterday so I've not used it in live starter yet, but it's been spinning water around perfect for a few hours now. I had to adjust my magnets to get the stir bar centered at first, but after that... no worries!
This was a neat project. I got to merge my four favorite interests, science, homebrewing, cigars and computers. (used a fan from an old Compaq server and the magnets from an old ~200mb hard drive)
