Whenever anyone says "3D printers can make anything" there is an immediate response from the uninitiated: Oh, so can it print a 3D printer?
It's difficult not to go straight into eye-roll mode whenever this is asked. Mostly because if someone is asking it it shows that they know nothing about 3D printing. But then I remember that there are likely 10,000 people learning about 3D printing for the first time today and I realize I need check myself and answer the question.
The short answer is RepRap. The long answer is, yes and no. No you can not press a "3D printer" button on your 3D printer and get a second, slightly smaller 3D printer. However 3D printers can print their own parts, my own makerbot has printed several upgrades for itself, and parts that can be used to, yes, make another 3D printer. But not all of the parts of a 3D printer are 3D printable. Specifically the electronics and stepper motors. There have been projects to make a 3D printer that prints circuit boards in solder, but so far none of them have been really successful, and even then there's the electrical components that would need to be added to the board diagram that could not be printed. Is it possible that these things could be printed one day? Sure, it's possible. But for now the best we have is RepRaps claim that a RepRap can make about 50% of it's own parts.
Now to be fair the initial assertion that a 3D printer can make anything is silly and wrong. There is no end of things a 3D printer can make, but there are limits to what it can make. Those limits are being pushed every day, but there's no way for a fully functional 3D printer to pop from the build surface of another 3D printer yet.
So there's your dose of reality. Now that your expectations have been properly trimmed go explore what 3D printers can do and be amazed.