How did the Ring create the Dougy?
I don't think we know that the ring created Dougie.
Most likely scenario is that Doppel-Dale created Dougie (as part of his plan to escape return to the Black Lodge). But Dougie was wearing the ring which we know protected Laura from being possessed by BOB in FWWM. I don't think we know why Dougie was wearing the ring yet, it could well have something to do with his creation.
Yeah Evil Coop created Dougie as a plan to not go back to the BL. Maybe he was wearing it to not be possessed by other spirits, or it is part of his creation because when he got in the BL, his hand that was the ring disappeared and then the whole Dougie became black smoke and that small golden ball took his place.
What do you guys think about Bad Dale intentionally putting the ring on Dougy, so that when he's returned to the BL, ring goes there with him and therefore making it much easier for Bob to possess people, for instance Good Dale?
But then again, can't Mike simply get out of the lodge with the ring as he did in the past?
I had thought it was all about protecting people who have the attention of the black lodge dwellers from being possessed by BOB... I guess if BOB entered Dougie than Mr.C's plan wouldn't work? There's some interesting points on the ring in this wiki... http://twinpeaks.wikia.com/wiki/Owl_Cave_Ring