Lew look at the center of the boss on your beautiful shield, it too has the indentation of the jig, the concentric circles were not tooled/rolled into the leather freehand.  I am getting more confident about my theory.  The wheel was/is  used across  mediterranean N Africa and surely the red sea coast to include Somalia.  This jig need only be a simple wooden structure.   Tim
		 
		
		
		
		
		
		
		
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