Doing some late night/early morning research.... I think I may have found an answer to some questions about "ballistic" protection.... But, as always, it too has some drawbacks. 1) EPA and other agencies involved ? 2) Permissions, and permits, fees, inspections ? Here in Arizona, as in many other states, there is an over abundance of scrap or used tires...! Those tires were at one time, (unknown now, as my email to the "Department of Environmental Quality" in Phoenix, was returned to me as undeliverable!), allowed to be used in the construction of homes, "IF" they were filled with compacted/rammed earth, and were contained/covered in such a manner as to: a) not be exposed to the "public eye, b) not exposed, so as to allow them to be ignited. The basic tire, say a 15", 235 to 270, is approximately 28 inches in outside diameter, and vary from 6 to 9 inches in tread width. That would allow you to build a wall easily, that affords great resistance to ballisitcs, when filled with compacted earth. Singley stacked, it would take just a few to build a nice wall! By placing posts or poles thru them during the compacting process, it gives additional wall strength. To cover them, use of a metal mesh or fencing attached to the tires, allows the addition of external earth for a covering that will conceal the tires, and protect them from catching fire. Thirdly, use of deep rooting plants, will not only help conceal the entire wall, but maintains the soil from erosion. Back to do more research on this !