An original production used set of alien bolos used to catch and abduct the townspeople of Absolution in Jon Favreau's Cowboys & Aliens.

These were beautifully made by Legacy Effects for the film. Although they look like a simple rubber prop on first inspection, they are actually incredibly well engineered and contain strong neodymium magnets and were literally used to catch and lift the actors and stuntmen on set.

They can be seen especially clearly in the making of special features on the blu ray release.