The big advantage of having a 3d printer handy? Quick iteration.
If I need to be perfectly honest, the main job for the new printer was printing out some unusual freight doors for a model I was building. Here are some of the Guggenhime and Company packing house freight doors, 3d printed and temporarily glued on my J.S. Roberts packing house model.
Over the last week, I've already done three tweaks of the 3d model for the door. I figured out Tuesday that the model had areas that were too thin to print, and so thickened the base, the handle, and the brackets which hung the door from the tracks. I also found the door was too small for openings I'd cut in the model, so I lengthened the door to ten feet tall. Wednesday's part kept having the track break off during removal, so I added a support piece to protect it. (The doors in the picture are Thursday night's prints.) Friday night, I added a door stop to the left side, added a weather strip above the track to match the photos. (Friday night's prints aren't painted or photographed yet, just wait.)
The real Guggenhime packing house also had two doors, each sliding open in a different direction. With the 3d model, it was trivial to flip one print to make a mirror image. I'd also be able to print some O (1/48) scale doors by scaling up my HO (1/87) model if I wanted to build some larger models.
All these tweaks over three days compared to a month and two rounds with Shapeways telling me, quite correctly, that my original model was too thin to print reliably. Getting told that by a web page that a print won't work is one thing; seeing the warped or incompletely printed details makes the lesson more convincing.
[Photo of Guggenhime & Company freight door from John C. Gordon collection at San Jose State University.]