I am a medical technician (I repair electronics, that repair humans), and in this field, not many plastic objects can be printed (everything needs to be auto-claved). 

But once in a while the carpenters, electricians or someone else comes to me and asks: "Can you print one of these?" 

YES! 

So far not many objects has been printed, but some of the simpelts, is the most cost-saving. 

The first image from OpenSCAD, is a tiny spacer, used in a washing-machine door. The spacer goes on the two rods holding the door. These wear down over time, going more and more loose. And the door starts clapping, clacking, clicking and what-not when it's washing. A spacer cannot be bought, unless you buy the whole door. That's $800. So these spacers cost next to nothing to produce a lot of. Cheap, works like a charm. Saving the hospital at least $4000 now. 

Next is my own calipers (Nevermind the broken plexiglass, happened after printing.) It was printed on the original PrintrBot (My first printer), actually was my second print on the PrintrBot. The file are long gone, this was done in 2012 I think. 

Last is the BRIO Train my son has fallen in love with. Broke a wheel the poor little train. OpenSCAD/RepRap-XY to the rescue! Happy son again!