This is a bike chain. fidget toy, based on Pdb6251's “brock split ring” model.

Note that the split ring contains an upper and lower ring segment, separated by a 0.2mm gap. This will appear as a floating segment when sliced – but it prints fine (albeit slightly fused).

Assembly instructions:

1. Split the rings using a small flat screwdriver or dill knife, as pictured. They should separate easily once started, as the layers are not well adhered.
2. Link the split rings like a chain.
3. Attach one figure 8 segment to each split ring, forming a linger chain: figure-8, ring, ring, figure-8
4. Attach the open hole of one figure-8 segment to the opposing ring (step 4 in the figure)
5. Attach the open hold of the remaining figure-8 right to the opposing ring (step 5 in the figure)