Building a birdhouse is beating me

Keep it simple and it's a nice weekend job. Use plain untreated wood, cedar or pine about 3/4 inch thick, and don't paint or treat the inside. The things that matter to the birds: - hole size sets who moves in. Check what you want and size it, around 1 1/8 inch suits wrens and chickadees, about 1 1/2 inch for bluebirds - no perch under the hole, it only helps predators - a few drainage holes in the floor and small vent gaps under the roof - a side or roof that opens, so you can clear the old nest out at the end of the season Mount it before nesting season starts, and put it facing away from the prevailing wind. What's tripping you up, the cuts or the roof?