allright, the RFID-things are looking good....
the goal is to sense the difference between the different objects, so you can distinguish between obj A and obj B, C and so on!
do you think with the metaldetector you could archieve this, for example big piece small piece, different kinds of metal?
(its about peolple going around in the garden, searching for things in the earth and that each person can find the same object in the same place with his device. devices would be something like tablet-pc+arduino+sensor)
#thanks, andy