Redrocker,
The frame is from a local company here in Ireland. They make it up in their own workshops.
Having seen it erected and the detail of the construction, I could have fabricated the frame myself. The biggest problem would have been space to set out and weld up. They are obviously geared to do this kind of work and have jigs set to create the framing. The profiled sheeting is off the shelf and the roller door comes from a local supplier also.
Given the time and space, I might have had a go.
That said, the workmanship is very good, they build these day in and day out and at the end of it I have a finished quality product. If I had done it myself, it might not look so complete even several years from now.
Here's an internal shot gives an idea of the positioning of the roller door.
Nigel