Originally Posted by Fredly00

I remember a long time ago watching TV and they discussed Alcatraz
and its bar design, basically an internal solid bar was inside of the visible
bar, and if you cut(hacksaw) through the outside bar, once you got to the inside bar
it would spin freely when you tried to hack it.. of course you'd need to
somehow crush proof the outer layer so that you couldn't crush it to stop the internal
one from rotating.