Cider Kit has made a really bad eggy smell. Will this go away?

OK all. My first cider try. I used a Brewers Best apple cider kit. After fermentation was done (about 10 days), I opened it to be knocked over by sulphur smell, aka rhino farts. However, it tasted ok and gravity was right on at 1.004. This has not gone to bottle yet. I saw some suggestions about adding copper, so I cut a piece of standard plumbing copper pipe I had laying around, 1/2 inch I think, long enough to be over the top of the liquid, but still be able to close my fermenter. I used sandpaper to brighten the outside, ran a small piece through the inside, then quick wash and sanitize. I stirred the cider lightly with it and left in there and sealed it back up. Checked after a day and it was significantly better. Another light stir and closed it. Next day, the smell was completely gone! It cost $0.

Sulphur needs to gas off, it's usually from a slow fermentation that wasn't vigorous enough.

If it's already attenuated there's a couple solutions. But both require putting the bottled cider back into a fermentor.

1) boost it up as a douple cider or Apple wine 4lb cane sugar to 5gal will give it +.040 points, then you can pitch a wine yeast to get it going again.

2) Use C02 to gas it off. Either use a hose to the bottom of the fermentor and give it slow c02 to simulate the c02 in a fermentation, or keg and force carbonate the release c02 by shaking and releasing the valve. Do either until no sulfur is smelled.

Some yeast strains give sulfur smell during fermentation. That's perfectly normal. If it's in the air, it's no longer in your brew! The fact you can smell it so strongly indicates it is, literally, going away now. It comes from metabolism of sulfur amino-acids. Sooner they are degenerated and sulfur is released, the less chance it'll get released in the bottle.

If it's already in the bottles, then it either is infection, or you bottled too soon. If that's the former, sorry, nothing you can do. If later, you can try to pour it back to fermentation vessel, add fresh yeast and give it more time. It won't get better in closed bottles, because sulfur gases have no way to escape them. Airlock or blowoff tube will work all right.

If it'll still smell like that after two weeks, then you will have a problem. But right now it's nothing to worry about.