Here's my take on the 3D printed birdhouse.
Included on the first tab in Customizer are 6 prebuilt birdhouse designs, each designed to be the "dream home" for a specific bird. I've also included the ability to add a text label to the front of each house (do birds have addresses?). Additionally all of my birdhouse designs incorporate venting to keep our fine feathered friends nice and comfortable (birds get hot too you know) which was suggested online.
I used this document to create houses at appropriate dimensions for whatever kind of bird you're trying to house. You can read more about birdhouse building guidelines here:
On the "Custom" tab in Customizer you will find sliders that allow you to create a totally customized living arrangements for your feathered friends.