Im trying to make a aluminum ring. I want it to be rock hard. PLZZAnswers that work get best answerFirst off, use the right alloy. Making the right alloys yourself is a recipe for disaster so it is best to buy them. There are a number of inexpensive alloys of aluminum that can be hard enough to be used as a ring. 5000 series, 6000 series and 7000 series are all pretty hard. If the alloy has a T in front of it, that means you can temper it by heating it then cooling it at a given rate (usually fast). To make the surface just a little bit harder, you can then anodize it (check out the yahoo group anodizing 101 for details - you can get some really pretty colors this way) and seal it. You can also coat it with a thin layer of a clear acrylic. Of course, if you really want ROCK hard, you can oxidize it, combine it with oxygen to make Al2O3 which is corundum, more commonly known as ruby/sapphire - one of the hardest materials known to man. You could also look up someone on the web that makes synthetic rubies and ask them to make you a ring from the ruby itself...then maybe do some engraving and gold leaf on it so that the metal is set in the gem rather than vice versa! That would be pretty cool! Also about as hard as you can get and totally unique.Dont use foil from the kitchen. Pure and simple. Get someone to machine you a piece of solid aluminum. You can\'t change the metallurgical properties of metal.use a hard alloy like 7075 and heat treat itOther related question