3D printers are an interesting example. Interesting innovation, but doesn't seem to be making money.

The things we need, actual wealth, as an anon on nab put it, is useful stuff, like tools, and resources.

Currencies seem to pop up when people trade and barter. If not bills then tins of meat, or cigarettes, or whatever else people barter with. Number of livestock has been used as a measure of wealth.

I'm also not sure what to make of "holding things in common". I've heard of the "tragedy of the commons," where nobody will take care of it. And people exploit each other all the time -- actually protected private property can help project people from exploitation. But it also creates this hoarding behavior. I feel better when I am cooperating with others to make something nice, together, as a group working together honestly for the good of the group. Everything feels much more natural to me that way... until someone takes advantage of the group or selfishly acts against the common interest. I also don't like being controlled by a group, I like being able to do what I want even if the majority of the group doesn't want me to. But I don't like when other people do that same thing when it's something I want them not to do, heh.