I have even heard of a 3D printer that is made exclusively from parts that can be printed on that same printer. So once you've got one you can print other printers for your friends.
You are probably thinking of
RepRap, although you still need to buy various metal bits.
It is however completely open source, including all the designs for the electronics, so you just need to scale it up a bit to make yourself a full sized aircraft.
Also, for those who haven't already found the link elsewhere, there is a video of the plane in action
here