I designed the structure around materials that are available at any big box hardware store. The ribs are each made from two sections of 10′ chain link fence top-rail. The end-walls and base are made from pressure treated lumber. To keep cost and waste down, I optimized around dimensional lumber sizes and ended up with a 12’x16′ footprint.
I connected the metal ribs to the wooden frame using a combination of electrical conduit straps and 3″ deck screws which I drove through pre-drilled holes in the pipe.
I had to order the materials for the covering online. The plastic is a special UV treated 6 mil greenhouse film that is supposed to last 4 years. It’s held in place using wiggle wire channel lock. This stuff is awesome. You jut pull the plastic over the channel and then wiggle the wire into place. The wire acts as a spring pushing the plastic against the channel keeping everything secure.