Let suppose that inside a some layer of foil (for instance aluminium) there are many tiny nanorobots encapsulated between molecular structure of the layer.
Do if you hit all over the layer with a hammer you will destroy ( or disable ) them ?
If you hit the foil, sitting on a steel anvil, with a very smooth faced hammer, you might get one or two. A 20nm robot would easily fit into a pore on the face of the hammer so not much damage would be expected.