There are spray lacquers available that give a variety of antique finishes. They are usually sold for Brass, & can be found in Hardware stores.

A quick search has some recommending a muriatic acid rinse and others say you should just take a leak on the stuff.

I've soaked brass hinges in vinegar with pieces of steel wool, and that's worked really well.

I'm at a loss.

Instead of ruining your finish, it may be better to put something on top of it to make it look aged. Muraic acid is hydrochoric acid, & can be very risky to use unless one is experienced w/ cutting it , & timing it properly. If you are just a little bit off, it will take all the plating from your hardware before you know it .

can you name some products maybe? something maybe on ebay?

I second putting something over it rather than acid dipping. It is your gear, and you will do with it as you wish, but once you remove the finish there is little left to protect it...and the aging process you start will continue until it eventually fails (in the hot rod world, they call it Rat Rods). This is the only reason I don't like speeding the age process...it leads to failure. I doubt you would enjoy your kit breaking on stage in the middle of a show.

Many people have used different paints and finishes with different success...do a Youtube search on paint aged metal for more ideas. I also saw on the Les Paul forums, a member aged his pickup covers with vinegar...but I am not sure what it does to the finish. Another thing to factor in your decision...pickup covers are not an integral part like hoops or lugs, and if he breaks them, it's not the end of the world.

I was talking with my son who does a bit of this on his guitar hardware. He uses "Etch Solution" for electric circut boards found at Radio Shack and the likes. He mixes it 1 to 1 with water. It's expensive like $10 for a pint. He submerges the part for 15-30 seconds max. Then flush/rinse very well with water. He said for something big as a drum hoop you might want to use a sponge brush to apply it. This would take 30-60 seconds as it's not submerged in solution. You'd need to practice on something to get the timing right. This applys a light layer tarnish. After time on guitar parts it can wear off and expose the shiney plating underneath. So you maybe would want to clear it with something possibly for longer lasting results. It's just a look some guys really like and want. The "rat rod" thing like Fordman mentioned if you will. Lots of good advice by everone here. Maybe try a few and see which nets the best results for your application.