A Tripod's Arm
Besides my pencil case, I think this is the only item that has stayed with me for as long as I can remember. It has even managed to make it through two changes in residence, the former of which was between different countries.
As a child, I used to love playing with the tripod. I would unscrew it, stand it, pretend to be an ace photographer and observe it from various angles, then screw it back on and safely place it back to where it belonged.
And no one would be any the wiser.