Apparently the "CUP HOLDER" has a long history. The 1944 Spitfire cupholder above has me a tad confused about the manufacturing process. I am looking at the encased wired that is running the perimeter of the sloped top side edges.
I think this is simply a way of terminating the sheet metal so as not to leave an overly sharp edge or snag points. In order to create it, I originally thought it was just an edge tab rolled over to form a tube then the wire was inserted. Then I thought they might of used the wire are part of the forming process and rolled the edge around it. My final thought was that its actually a circular tube with 26 Gauge wall with a 14 Gauge wire insert as described at the top of the page item "C".
So my question is how would one make this "tube" of a different gauge than the adjacent sheet metal which it would be attached to? I noted no welding symbols so I am curious as to the process.