This library comes completely assembled. It measures 20"x13"x17", the roof is 24"x17". I make these our of Pine/aspen, the roof is made of 5/8" exterior grade Canadian Plywood. Instructions on how to mount it on a post are included. No need for brackets or special hardware. The roof is not completely flat. I do make sure there's a slight pitch on it so water won't puddle.
Lexan is acrylic and much better quality than Plexiglas for this application. Instead of clipping it to the back of the door I cut a groove into the door frame and insert the window adding sturdiness to the door.
For those who aren't sure what these are.....you decorate them and mount them outside of your home/cottage/RV, fill it with used books. People come along, take a book and leave one in return.
Or you and your neighbours can use it as a pantry. Fill it with dry goods (food, diapers, towels, etc) to help others out in need.