Theory: Rinne Tensei+Izanagi=Creation of things jutsu
Sorry if this theory has been said before.
So just as the title says, I have my own theory about the Creation of all things technique. I believe that Izanagi and Rinne Tensei are simply two halves of a complete technique. Izanagi ofcorse being the yin half, and Rinne Tensei being the yang half.
Creation Of All Things Technique
Look carefully at the middle panel, it's a perfect explanation of what the creation of all things technique does. It uses spiritual yin release to create form from nothing, then uses physical yang release to breathe life into that form.
This is the process that the Sage used to create the tailed beast's bodies and bring them to life.
Now let's split this up and break down the technique into it's two parts.
Now we know that Izanagi is yin release, and based on spiritual energy, and that it can create form and shape from nothing (not to get confused with Tsukuyomi, which simply creates illusions inside an imaginary world, not the real world). A perfect Izanagi can be used to make one's imaginations real in the real world, just like the Sage made the bodies of the tailed beasts real. Remember when Danzo kept getting hit by Sasuke during their fight? His Izanagi seemingly created a new body for him every time. It's important to understand that Danzo's real body was being attacked every time. Karin was there to see the entire thing. Danzo simply used Izanagi to imagine that he wasn't really being damaged, so Izanagi created an undamaged body. But Danzo couldn't create a separate clone and give it separate life, he would need Rinne Tensei for that.
Now remember the cost of using Izanagi is that your sharingan goes blind.
We know that Rinne Tensei can bring back the dead by infusing life force energy into a body. The downside of Rinne Tensei is that you have to revive someone recently dead. I think the answer as to why this is so relies in the body of the deceased. We know that dead bodies begin to decompose as soon as you die, and Rigor Mortis (when the body stiffens) sets in somewhere within the first 12 hours after you die. Rinne Tensei puts life energy into an existing body. It doesn't create a new body like Izanagi can do. Therefore it stands to reason that the reason Rinne Tensei needs to be used on someone who hasn't died recently is because the body still needs to be usable. If you wait too long, the body would no longer be capable of sustaining life anymore.
The cost of using Rinne Tensei is that you die. Now it's unclear as to whether or not Nagato died because of the jutsu or because he used too much chakra, but remember the conversation with Obito and Madara?
Obito said specifically that he would be throwing his life away if he used Rinne Tensei, so clearly Rinne Tensei does lead to death. Konan probably didn't know much about the Rinnegan anyway, and probably didn't know that Nagato would've died using that jutsu regardless.
If you put both of these techniques together, you could not only create a brand new body from thin air, but you could also breathe life into it, therefore Rinne Tensei+Izanagi=Creation of all things. It's also important to keep in mind that Danzo did not have have a perfect Izanagi, and believe it or not, Nagato probably didn't have a perfect Rinne Tensei either.
Now I know some of you will point out that you need senju+uchiha dna to get Rinnegan in order to use Rinne Tensei, which I agree. But also remember that you need senju+uchiha dna to use Izanagi too.
So this means that both techniques require some portion of the sage's dna (senju+uchiha) to be used. And if you get someone who can perfectly control both halves of the dna, then they are able to use Rinne Tensei without dying, and use Izanagi without going blind, meaning they have access to Creation of All Things
A little sidenote, I also believe that the orginal plan of Madara was to have Obito use Izanagi to make a new body for Madara, and have Nagato use Rinne Tensei to breathe life into it, thus Nagato would've died but Obito would've lived with Madara. Obito may have a perfect Izanagi, but he hasn't had the time to perfect his Rinnegan skills, so using Rinne Tensei would've most likely killed him as he pointed out with Madara. So I guess that's how my theory correlates with the plot.
So that's it, I hope you enjoyed reading. Sorry if it's confusing and not well organized. I'm multitasking at the moment. Let me know what you think and I'll be happy to openly debate anything and I will correct things and credit you if you prove something wrong. Thanks!