The secret ingredient (beyond a solid design based on Newton and “the physics”) is the instrument-grade ruby sphere. You heard me right, I said ruby.

This type of manufactured ruby is used in things like Rolex watches, super-precision measuring instruments, fiber optic transmission lines, and other really expensive and/or sciency stuff. The hardness is 9 on the Mohs scale. Diamond is one of the few harder materials and scores a perfect 10. That alone is awesome!

I know, I know. How tough is it? THIS tough.

That's a ruby smashed between the steel top of my bench-vise and a 16oz. dead blow hammer. Yes, I hit it really hard. Yes, it did break. It's tough…not indestructible. Just treat it like a ruby and you should be fine. If you treat it irresponsibly…it will break, as demonstrated above :)