Twelve years ago, I found an old porch light at an estate auction. I knew instantly that I wanted to make a birdhouse out of it. I had a stack of old tiles, and it just worked. The house with the chipmunk on top is the one that I made twelve years ago. It has been hanging in my backyard ever since. Wisconsin Winters to Wisconsin Summers, year after year and it still looks great.
The one I made for purposes of this Instructable is the green one. I found the fixture on Ebay after a search for hanging porch light, swag light, porch lantern.
However, I have made many of these birdhouses and have found these old lights at Goodwill to garage sales. Just keep your eyes open.