We used 3/4" PVC pipe, connectors, 3.5 mil plastic to cover it
first we attached fasteners to the inside of the beds to hold the pipes
we cut the pipes to size
and put the pipes in the fasteners and bent them to the middle and attached them with connectors
once we had the three hoops on we attached the spine
then it was time to get the plastic cover ready, we got a single sheet that we cut in half, stapled to a thin piece of wood on either side, stretched it over the hoops and screwed the wood into the beds for a tight seal on the sides
we used 1"PVC pipe and cut it to 2" pieces and cut about a quarter of the pipe out, filed it down and used those to clip the plastic to the hoops
the view from inside
After all our hard work yesterday I went to check the house this morning and discovered that it was warm and moist inside.
Some of the seeds I'd started inside have been coming up so I moved them to their new hoop home.