I printed, but I'm still refining to make it easier to cleanout and assemble the front plate. Based upon Lowes Birdhouse which has a roof which commonly breaks apart into pieces. Our barn swallows love the original wooden ones (see last picture), but they only last 2 years at best before they start to break apart. After having replaced approximately 10 of our 30 that I've purchased, Id like to start printing them.

I designed it to be printed on a Prusa mk3 printer in 3 separate pieces. It was my first design and first thing I designed with Fusion360 or cad program since...1997 shop class, so bear with me =)

It has 3 components which are designed to be printed in the orientation shown:
1) Roof and rear backplate (no support needed if printing in orientation shown)
2) Bottom/floor and rear backplate (Support from bed only)
3) Front plate which can be screwed off from the front and sides. The opening can be adjusted for what particular bird you'd prefer. (Support from bed only in version v2)

Bond the sections together using crazyglue, a 3D pen or anything else that will maintain structure. Print using PETG, preferentially using a somewhat darker color which will not be quite as sensitive to UV light.

UPDATE 8/28/2018
The top plate (roof) is updated so it doesn't protrude and strike the roof
angle. I re-designed the front with a flange so it can simply press against the top and bottom plate instead of trying to screw into the sides. To do so, the front flange was adjusted so it extends out further. The photographs show the original version, but have the same basic concept for the remainder of the print.

UPDATE 5/09/2019
The backplate is updated so it has a ledge for a metal square of wire to serve as a base for the nest. Therefore all droppings will fall to the bottom of the birdhouse, away from the bottom twigs. This is identical to how the purchased version is. There are also holes along the sides and rear plate to assist with mounting to support the birdhouse as well as screws for screws for the front.

UPDATE 7/07/2019
It was silly to use a wire grid rather than just designing one specifically for the birdhouse. See attached.

Fusion 360 files: https://a360.co/2Q9dkD2