I was thinking about this and not to hijack the thread, but I have some magnets and I have been having issues with nails in my driveway (gravel) where the roofers were. So I grabbed some little magnets that came out of hard drives and was going to put them on a board attached to some type of pole, thus sweep over the gravel and pick these nails up. Then I started to think this is a homemade metal detector! I'm sure that "real" metal detectors have magnets in them, and again started to think about "revenge of the nerds" where they were stranded on an island and dexter made a homemade one. I'm going to find out if I can use these magnets to make one.