In 2011, my daughter and I built a rather large 4-family wooden birdhouse for the Lexington, KY Arboretum's Birdhouse Display and Benefit Auction. We didn't want to sell it, so we put up an Instructable ( http://www.instructables.com/id/How-to-make-the-bird-house/ ) detailing how to build one yourself. Now, we've made it much easier... although this 1/2-scale structure houses just one family.
Features? Sized for various small bird species, removable roof for cleaning, printed with 5-10% fill provides air gap thermal barrier, angled vent & floor drain slots, internal "ladder" to ease bird egress, darn cute design. ;-)
Simply print 2 fronts, a body, and a roof. Paint or print the parts in appropriate colors; painting external parts can improve weather resistance. Glue/weld the fronts on the body (which is also used for mounting). The roof is held in place by a couple of pieces of velcro stuck on the inside of the front plates.
Printed in PLA on MakerGear M2 using 0.3mm extrusion, single side wall and two top/bottom walls, 5% fill on roof, 10% fill elsewhere. Print times: front 1 hour, body 4 hours, roof 2 hours -- total about 8 hours.