They are 15 gallon drums. I cut a 12 inch wide opening from the top ridge to the bottom ridge. Then I cut the drum in half and push the top half over the bottom half and use self tapping screws to hold them in place. I use the piece I removed from the drum as an awning over the opening. The handle on top allows he to move the broody hen without disturbing her. I get the drums from the Pittsburg Recycling center fairly reasonable I also have used some of the drums for watering by installing drinking cups about 3 inches from the bottom of the 15 gallon drums.