Meanings of using this thing in English

I've been using this thing for a while.

I probably should never get one, because I can just see myself getting beaten up on the Subway using this thing.

Losing billions of citizens in a protracted war of attrition would be, moral, but using this thing to kill millions would be immoral?

They were then using this thing that we had built to answer very specific questions about how corals react to elevated carbon dioxide, for instance.