I've used JB weld on rod guides wrap. It is not always consistent, sometimes to get good results you might have to be lucky. One rod I coated the ferrule wrap with JB weld epoxy and it turned out great, it was as perfect and smooth and hard as the real thing.
Make sure to mix really well and thoroughly. Make sure you as equal amounts of hardener and resin as possible. Don't use heat and you will have longer working time. Bubbles is a side effect, a price to pay for longer working time. Use heat and it will set much too soon. Rotate the rod to level the epoxy while it cures. The warmer environment you do this in, the better.