I think I have or had one of those. It looks like a hand crank for an old car (smaller version) with a hook at one end. You wrapped whatever you were trying to contain, made a loop in the end, inserted the hook and began to turn the handle, the hook would cause the wire to tighten upon itself.
Something like these only stronger:
Wire twister Wire twister or
Milbar wire twister Concrete Form Twister wire-twisting-pliers Pete