Magnetizer/Demagnetizer

Richard Griot, the guy who puts out the catalog where I found this, wrote about it: "One of the most useful items I have in my 'bag of tricks.'"

More:

There are times when I want to have my screwdriver magnetized so that I don't drop a precious fastener down to where I can't reach it.

I also like to magnetize my files so that iron filings don't get into places they're not supposed to (oil lines, etc.)!

Magnetize and demagnetize screwdriver blades, tweezers, etc.

Made in Germany.

$9.99 here.

No moving parts.

At least, none that you'll be able to see — Earthling.