Primary effort comes from the chain generator. Attached scad file simply has a couple of lines added to generate the cylinders on the ends, and some tabs to hold it in place temporarily. Found it was warping and peeling back mid print - being so long and narrow, and those did the trick.

The STL should be relatively clean. Scale and print. There will be some trimming to clean and separate the links, as the scaffolding is a little messy.