These are all pretty ingenious actually, since they probably don't have much access to Kevlar helmets or hockey helmets.
The "Standard Box":
Nothing beats the "Classic Brick Hat":
The "Broken Pail":
The "Stew Kettle":
The "Round Pounded Thingy":
And the old standby, the "Twin-Baguette Earmuffs and Ham Salad Roll Cover":
Special thanks to Fran for sending me these gem...