Read switch

I would like to either be told how, or shown a source that shows me how to build a read switch (hardware). I know you can buy these at radioshack, but I need to build it for school.

Any help would be great, I searched google for a while, but found nothing.

do you mean a reed switch?

basically all you need it some material thats magenetic and is flexible - if tin foil was ferrous that would be ideal but its not so you'll have to do some thinking...

attach the flexible materil to a nail and align it so that it touchs when its draw towards the magnet the contact will close and connect with the other nail, you could probably achieve this with a piece of wire bent into a hoop shape?

i tell you something for 12p it would be allot quicker and more effiecent (and cheaper) to go to radio shack and buy one....

i2c