the cheep option, which takes some time is.... make 50 of them.
50x iron nails.(ie, you can pick them up with a magnet
50x springs preferably fit onto the nails with no bodging. if not some means of attaching one end to nail.
50x short tubes, closed at one end. fits nail and spring.
50 cheep clicky biros?
massive coil of thin insulated wire.
drill. (trust me, you want to buy this if you havent got one!)
shorten nail so the spring covers most of the nail. a little extra nail is needed. kind of like
take a tube, cover spring, and have a hole to fit the nail.
prevent nail from droping out.
this should mean that the nail can be pushed in and out.
wrap a coil of wire to make an electromagnet, and place this so it pulls the nail up.
if spring pushes the nail up. ie base;spring;nail;hole
coil can be wraped around base to pull nail down.
insulation tape to stop coil unwraping. leavers can make a bigger movement.