There are two designs included with this model. One has a strategically weak center section on each of the connecting rings. This is so that separately printed pieces can be attached by first crushing the weakened section with a pair of pliers and then pulling the extra plastic free. Some sanding of the edges might be necessary to attach two pieces together.

There is also a version that has no weakened part in the rings for stronger pieces. When chaining pieces together, make sure the two pieces are not intersected with each other. The pieces above were printed with 100% infill, but this not necessary four piece integrating, 50% works just as well.

Good luck! I am happy to receive feedback.