Or they destroying us. Depending on who looks first.

Why not? All you need is to hold it suspended, without allowing it to touch anything. Simples. Then you open the container on one side and let the hole inside suck stuff in. The ultimate vacuum cleaner. Brilliant. The unobtainium shell will shield you from the gamma radiation emitted by the stuff gathering speed as it falls in.

I would buy an extended warranty if I were you, though. Black holes small enough to fit in a ride-on mower won't last very long due to Hawking radiation. And they tend to pop with quite a bang. In the order of megatons of TNT.