Only three examples of supramolecular n-Borromean rings have been identified to date. Here we report on the first application of the tools of metric engineering to the design of this fascinating class of interwoven supramolecular structures. Halogen bonding drives the self-assembly of naked iodide ions with alfa,omega-diiodoperfluoroalkanes into n-Borromean rings whose metric size can simply be tuned by varying the length of the diiodoperfluoroalkane used.