Mike explained the model well and WIM showed an example, thanks.
I got to the same results by editing two cross sections and adjusting corner reliefs through trial and error. I thought it would be more intuitive as it is such a simple part in the real world. I don't understand the negative depth value I'm punching in at the corner relief, closed, orientation left or right values. I'm sure there is an explaination. I like the model challenge though. It's like a puzzle. My jpeg shows my development left to right. Far right unfolds to a simple strap band. Attached thumbnail(s)