Entrepreneuring With A MakerBot

There's a terrific story on Solidsmack of how an entrepreneur turned a MakerBot personal 3D printer into a viable business. 
 
The folks at I Heart Engineering wondered whether they could treat a MakerBot Thing-O-Matic as a kind of miniature factory for a startup business. They designed a specific adaptor for hooking Microsoft Kinect sensors to standard tripods, which seems like a reasonably popular idea to us. They tested the viability of the proposed product on the Shapeways 3D print service, figuring that if it sold there, it could be made directly on their MakerBot and sold directly at a profit. 
 
The result? It was indeed profitable. They received more than sufficient orders to cover their costs and proved that it is possible to launch at least a small manufacturing business with your personal 3D printer. They say:
 
While less quantifiable, we also believe that the 3D printer allows us to offer products with limited or unknown demand without losing vast sums of money. There also appears to be sales driven specifically by offering wide variety of 3D print accessories for our robotics products.
 
You can make a business by going under the radar and producing small quantities of unique items. Of course, if the item is popular, you'll be blown away by Chinese mass production, so you must stay within a niche.  
 
What will your business be?