We started with different sized pens already enclosed with metal wire Panels. Hog panels work best.
We used 3/4" PVC Electrical Conduit for the frame. We bent the Conduit into an arch shape by securing the ends of the Conduit to the panels with Plastic Cable Ties. Each "Rafter" was spaced aproximately 4' on center.
We connected the Rafters with a Conduit "Ridge" fastened with self drilling screws..
Bird Netting (25' wide) was stretched over the frame and fastened to the
panels with Plastic Cable Ties. We started working on a 12' wide
pen. We used 2 1/2 lengths of Conduit per Rafter (25') and glued the joint.
It bent easily, but felt strong enough to support some weight.
It's worked well and should support some snow load--as well as the odd turkey looking for a place to perch. We tried wider pens (13'-15') but didn't like the results. We changed those to approximately 12' wide.