Concealment: Unconcealable, Slick
This is a small self-propelled cart, concealed as a barrel or other inconspicuous object. It is capable of carrying ten kilos or so over flat floors and perhaps one kilo over rough ground. Variants can be constructed to traverse water or even fly or jump very short distances.
The device will travel slowly along a pre-planned and predetermined route. Because it moves so slowly, it is unlikely that it will be noticed. It can traverse pipes and other areas humans can't go.
One use of the device is to carry a bomb into enemy territory. Another use could be to fetch some item in a high-security area or past bars or grilles impassable to humans.
Reprogramming a clockwork cart is as difficult as building one. The GM is encouraged to make the path of the clockwork device intriguing and exiting, with plenty of FixIt rolls.