Board Thread:Theories and Speculation/@comment-30168130-20170115054258/@comment-4912646-20170116053546

Maybe. The black rods are probably the oldest concept in this series that have yet to be explained (aside from Yin and Yang, which were eluded to way back in Part 1) so all we can really do is speculate. Until the fourth databook, there wasn't even anything officially linking the receivers to the Rinnegan, aside from Obito's vague Outer Path comment. And even then, all the databook said is "the user distributes the Rinnegan's trademark black receivers". So they're apparently a trademark of the Rinnegan, but that doesn't necessarily say it's the only way they can be created.