Was there anything stopping Sauron from making another "one ring"? Was he too weak since his separation from the ring to craft another? Or would it have taken a long time?
The quick answer is, "Yes, he was too weak." In Gandalf's words:
This is the One Ring that he lost many ages ago, to the great weakening of his power.
Now how, exactly, you want to interpret that might vary. After all, Sauron was certainly powerful enough to "reconstitute" himself, reorganize his armies, and sweep back into Mordor relatively early in the Third Age. But the Ring contained him, in a sense:
... it is his, and he let a great part of his own former power pass into it, so that he could rule all the others. (Gandalf)
(both quotes from The Fellowship Of The Ring, Chapter 2, "The Shadow Of The Past")
Even without the Ring, he still had the ability to control the others: in particular the rings of the Nazgûl. But it's at best highly questionable, as I read the material, whether he had enough power to create another Ring of the same power as the first.
Sauron placed an enormous amount of his own "strength and will" into the One Ring in order to make it powerful enough to dominate the 3, 7 and 9 rings. Although it's not explicitly stated, the fact that he expended vast resources on a search for the Ring over hundreds of years would strongly suggest that making another ring simply isn't an option.
More importantly, the One Ring was invested with sufficient power to rule all the other magic rings in Middle Earth. Since Sauron knows that the One Ring (described in the Silmarillion as a device of "surpassing potency") is still knocking about, if he made another less powerful ring to wear then he could find himself subject to the will of whoever wields the One Ring. That was something he absolutely couldn't risk.
Now the Elves made many rings; but secretly Sauron made One Ring to rule all the others, and their power was bound up with it, to be subject wholly to it and to last only so long as it too should last. And much of the strength and will of Sauron passed into that One Ring; for the power of the Elven-rings was very great, and that which should govern them must be a thing of surpassing potency; and Sauron forged it in the Mountain of Fire in the Land of Shadow. And while he wore the One Ring he could perceive all the things that were done by means of the lesser rings, and he could see and govern the very thoughts of those that wore them.