Rings - Solid rings, especially .10mm layers are almost unbreakable.
Links - Oblong links that connect the rings in whatever pattern you want.
Locks - Clips that hold the links closed tight and multiplies strength 5X.
The links have an overlapping Z that when locked with a clip allowed a link to hold over 15lbs (video below) This is the key to super stength. In the image and video you can see the link wildly distorted before the link opens. (2.2mm thick, .10mm layers, Prusament PLA My Silverness.
.10mm layers have been proven to be the strongest, so that is my default.
Feel free to make your own .15 or .20 gcode, but know strength will be reduced.
For infill I just run max perimeters so it's solid and strong as possible.
I created the models as strings to help keep them on the build plate and if one comes loose it doesn't ruin the whole batch. This is to help with overall success and you can go without if you like, raw models added at the bottom of the files tab.

The author marked this model as their own original creation.