Just to give you an idea of the static durability of this stuff, I used this stuff to help my dad fix an outdoor patio table last may. The umbrella had Mary Poppins'd off and ripped the center of the table all to hell. We had to pry up the surrounding tiles that were glued onto the table and chop out something like a 1 square foot section out of the middle of the main tabletop with an angle grinder leaving a square hole right through the table about 3/8" thick. Then we taped a piece of vaselined plywood to the underside as a form and poured in a layer of bondo glass on top of it. We used a single layer of coarse steel screen material running through it for reinforcement (the rest of the table has the existing steel welding mesh/fabric reinforcement running through some sort of lightweight concrete material that makes up the surface for the tiles to fix to) over the top of the first layer and then let it cure before we poured on a second layer. After that we drilled a hole through the center of the patch for the umbrella, siliconed the tiles back in place, had the guys at the granite store cut a hole in a sample tile that we used to replace the center tile that shattered in the accident, used a brass pipe fitting through the tile and into the patch for strength when using the umbrella, re-grouted the table, and sealed it. It has not been moved back in side once since we got done with it, and it has survived last summer, snowpocalypse over the winter, and the extreme heat of this summer and it has yet to warp, crack, or drop out of the bottom of the table.
If you feel like you need this particular form of overkill for your armor, it will not let you down! However, it is a bit heavier than normal bondo so take that into account. Also if you really need an extreme fix they do sell metal filled bondo which is a silver color, basically it's bondo with aluminum powder mixed in as a reinforcement. I can't speak as to the durability of this stuff on large scale applications but bondo claims that it can be tap and died as well as machined after it cures.
