The curved part is for concrete to make poles and stuff stay in the ground, stick that in the ground, put your pipe (or whatever) inside the tube and pour the concrete around it. We are trying to find where to get that at so we can make one like that. It is also on spools of wire at the hardware store and they will usually give you the empty spool FREE. We have had several spools given to us already and I have found a friends husband who sells stuff and he can get me the 1200 foot spools of sisal rope SOoooo cheap! I want one with the curved beds, Sirrahbeds looks just like the one I want to make for my babies for my bedroom.