I use them and it seems to work alright. The one I used was made by just taking the biggest shell you could buy. ( I think it was super mag but im not sure) and attacthing it to a conduit frame. It's pretty much the same design as a boughten one.The shell is still big enough to cover your whole upper body and a small part of your legs, but a bit smaller than the store-bought brands are. I read somewhere that a goose's size perseption is very poor, so they have a hard time distinguishing how big or small something really is, and thats supposedly 1 of the reasons the chairs dont stand out as much as they do to humans.