Fabulous script there NickE!
I have one criticism for you and a request.
Crit: Every alternating chain link that is created has flipped normals. Can you fix this?
Request. Would it be possible to create oblong chain links as well? Perhaps some kind of option would be available? (that would be awesome)
What you've done already is awesome, so great job.
Edit:
Another thing I noticed is that the script doesn't seem to take into account the thickness or hole size when creating the chain. So if you create different widths of chains, the chains intersect. It would be nice if the script did its best to make the chains go through one another. It wont be possible all the time with certain settings of course, but say the hole were too small for the chain to go through, it would just do the best it could perhaps having it go straight through the center.
Once again, fabulous job so far.