The first shot shows one of the mounting plates in position, the rod just slid into the tube, and the second shot shows the finished set in position. You really need to make the separate plates, either by fabricating the separately or by scoring the platicard and then add the tiny fixing buckles. Also, be aware that the number, and therefore the lengths of the individual plates varied over time.
That new model F looks great by the way. Must add it to my Xmas list - note to Dave at Forgebear, Don't let that IS-2 slip any futher or my Xmas list will be full already

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