Buy 12 pack of beer. Drink it haha. Turn the box in its side, top facing out. Cut box top in half fold other sides in. Fold box top in half making ledge in front then tape. I love making my nesting boxes this way because it is free and I never have to wash or worry about them getting to dirty. I just throw them away after a couple weeks or a month of use. i am sure this has been shared before but I think it is very valuable info. I love saving money, having clean boxes, and easy ideas. Hope someone benefits from this info.