There *are* 3D printers that can make saleable products. They are more often called Rapid Prototyping units, and have price tags that would scare the living daylights out of any normal, or even reasonably deep wallet. Some of them can do metal 3D printing (selective laser sintering or SLS, see this, it explains it well enough
).
As for the strength when printed on a consumer orientated printer, it's mainly down to the design of the part, and the infill method used when printing. I can't see a part printed with ABS filament using a decent honeycomb infill of 30-40% breaking, short of issues that would break the helmet it's attached and probably the noggin the helmet is resting on.
Searching for the ever elusive Underground Titty Bar.
DDDWH CC