In the original instance, the problem was about a black hole passing through a sheet of metal. However, even if the black hole were stationary and sitting in the center of a metal sheet, the mass contribution from the sheet of metal 'consumed' would be insufficient to expand the event horizon significantly. Remember the mass of the 1 foot radius black hole is approximately .0001 solar masses or 2e^26 kilograms. A sheet of metal isn't anywhere in the neighborhood of that kind of mass. As for subatomic 'tearing' due to tidal forces, the expansion of that radius would be as inconsequential as the expansion of the event horizon.