Ways to make money with your 3D printer

Has anyone thought of a good way to make extra money with their new 3D printer? Here are some of the ideas I have come up with. What do you think?

-Printing 3D printer parts and selling them online.
-Rapid prototyping for other businesses.
-Making moulds.
-Making models for architects or anyone that need on made.
-Printing custom bobble-head dolls of people using 123D.
-Printing and building 3D printers for other people.

Does anyone else have any good business ideas?

 

A spin off of the selling them online, depending on what it is Etsy could be a good outlet if it is houseware or art sort of deal. Could always give back and do a kickstarter campaign!

 

http://3dtopo.com/lostPLA/

http://www.thingiverse.com/thing:55415

 

Custom Lego bricks in glow-in-the dark or wood.

 

Actually, if the resolution was good enough, you could emboss someone's face onto the little Lego guy head.