In case the link does not work, it is a llama (alpaca!) shelter made by arching cattle panels, stabilizing them in that position with T posts, and using zip ties to secure a tarp to the exterior. The arch/tunnel is open on both ends for ventilation, which is critically important. You do not want a barn to be all sealed up tightly.
I don't want to use a tarp. Thinking...what else would work for a roof? Join and arch metal roofing over the stock panel?