If Bilbo took these rings to Mordor, he probably won’t mind too much if he’s lost them, because we can get him a next day delivery. These rings are meant for casting them into metal, so the Ring is likely forged in this fashion, 2016 style.
We can also dye these types of plastic into a darker shade of colors. Using economy cream material, turn time is as fast as 24 hours.
If you notice in this un-dyed picture of the rings, the left one is actually composed of 3 individual rings tied together, this is printed in one assembly.