While they've come down in price immensely ($400 versus tens of thousands of dollars), there's still the problem of making them appealing to the Average Joe. We have this once-exclusive technology shrunken down to fit on our kitchen counters, and we don't know what to do with them.
CGTrader, $4, knew that there were plenty of useful things you could make with a 3D printer, so they gathered up these $4. We added some of our own as well.