I finished a small greenhouse recently. 6X8 feet in size and about 7 feet tall. Windows on the front and back. I even ran electric to it. Plexiglass for the front and back but plastic wrap on the sides and the roof. I may change that in a year or two depending on finances. Tried to keep it around $500 and ended up spending about $600. Whole thing is built out or pressure treated wood and it is not on a foundation. Didn't have to get a building permit since it is considered a temporary structure. Finished the top windows recently but they are not in the picture.