Hi all, I have been frustrated with chain for HO scale models. the smallest I have seen, 40 links per inch, is still way too large for lots of HO stuff, and besides, the links are round, not oval or elongated and don't look right. So I tried an experiment that seems to work out pretty well. Here's a photo on my Grandt HO C&S caboose:
It's not really chain, but braided wire. This pic shows a larger version so you can see:
Take a piece of wire, (.004" copper for the "chain" on the caboose), and fold it in half around something like a nail or pin in a vise, to hold tension. Then twist the two ends together once or twice. Hold the middle of a second piece of wire at the twist, and fold both ends of the first piece crosswise to trap it. Then just alternate folding the second, first, second, first, etc. Mess with the tension you use, and the angle you pull at when you fold, and you can get longer, shorter, more or less round "links". It goes pretty fast, maybe takes one minute to make half an inch of chain, so you can practice a few times to get what you want. With the .004" wire you have to look really microscopically to see that it's not real, separate links. Larger sizes like the example in the second photo are not as convincing- you can see that the loops are continuous, not separate links.