Architectural Concept Models
There are a lot of great applications for 3D printing in the field of architecture.
Here is a mass model for a large building. The black material is the grounds with the road and parking lot recessed. The white material is an outline of the building. The overall scale is about 4" squared.
Here's a link to a video of the model in different orientations.
I'm sure that everyone has seen some kind of a scale model of a building at some point, so the idea of creating a physical representation of a planned building is certainly not new. What 3D printing does enable that is different than other model making techniques is the time and cost scale.
Time: This model was sent to me on a Saturday, I printed it that night, and delivered it the next day.
Cost: At this size, these can be made for under $50 if a good model is provided. (Of course, I can also create the model for you if you do not use 3D modeling programs.) At this cost, an architect can have several copies of the same model made or have several different concept models printed to present quickly to customers. When there are numerous firms bidding on the same job, you can make your firm stand out a little bit by leaving a copy of your model behind for each of the members of the committee.
You can also get really creative and try different things. The model can be painted. This model was printed in 2 colors, but more as-printed colors can be used as well.
Do you expect that your customer will give the model to their kids or grandkids? It can be sized to fit with a favorite train set or have connection feature built in so that it can be used with a favorite blocks set.
Maybe your customer is more of a workaholic type. Embed some kind of a useful office tool into the model like a business card holder or USB drive.
Big partier? Why not embed a bottle opener.
The options are pretty wide open.
Here is another example of 3D printed architectural model with more lower level detail. I've got to think that if I were selling high end houses, it might be worth my $$ to send prospective customers home with something like this. Or maybe send a good client home with a scale replica of a home they just purchased as a thank you gift.
http://www.thingiverse.com/thing:26244
Two-Story Spec House (pwc-phil) / CC BY 3.0