Hi, alot of antique dealer and appraisers would have a fit if people cleaned up brass and cooper items, only because it decress the value, you can have a professional do it at a cost!. There is a mild remindy though, combine equal parts of flour,salt and vinegar, mix into a past. Spread the past onto the metal, let it dry, and buff it off w/ a clean dry cloth.
You can clean an antique copper faucet. However, you may not want to. If you clean the piece it could lose its patina which takes away from its value. If you do clean it, use soap and water and be gentle.
Vinegar will do it.
There are several methods available to clean antique crystal decanters. Avoid putting them in the dishwasher, instead, use a mixture of 1 cup vinegar to 1 quart warm water to safely clean the decanters.
Antique lockets are delicate and require special cleaning techniques and procedures. A person can clean an antique locket safely and effectively by using a mixture of baking soda and water. A person can use a sponge dipped in the baking soda and water solution to softly rub the antique locket then let it air dry.
The molds are worth more than the value of the copper (provided they are indeed antique) so don't scrap them.
Vinegar.
Antique copper trays can be hand-hammered and coated in various materials such as silver or gold. They can be circular, square or rectangular and may have handles.
Take this to a reputable antique dealer
You can purchase antique copper on any online marketing like ebay or amazon. Great places and low prices overall. They can be in mint condition or kinda used.
You did not state what the sculpture was made from. This would determine how you clean it.
Copper oxides are soluble in acids.
Ideally through the fixture trap or clean out and NO chemicals