Most of us will be aware of the existence of home made fiddles. there are numerous videos on youtube of cigar box fiddles, candy tin fiddles etc. Why would you make your own fiddle? Well, some people just lake making things, and being creative. These days, you can buy a fiddle for very little money, thanks to mass production in China, and whilst these may not be brilliant, they are good enough for a beginner in most cases. It was not always so. In the depression years, when survival was a struggle, most people did not have money to spare for such things. Hard times breed desperate measures. People built instruments from what they could find. I believe there is a famous plywood fiddle in an American museum. Ireland, as we all know has a strong tradition of fiddle music. It also has a tradition of travelling people, some of whom made a living as sheet metal workers, making and mending pots and pans etc. These people were sometimes called Tinkers, although to some, this is regarded as derogatory. Some of these guys made fiddles out of sheet metal!. Remember we are talking about skilled people here. So these fiddlers had all the features of a standard fiddle, including the shape, F holes, and arching of the top and back. Producing this arching from flat sheet metal requires great skill, using special hammers and techniques. The ribs had flanges for soldering to the top and back, and putting a flange on a curved piece of sheet metal needs very special skills. The body was soldered together. The neck was sometimes recycled from a broken wooden fiddle, but examples exist of instruments with hollow tin necks. Tin fiddles were said to be not so loud as wooden fiddles which I find surprising. For more info, Google Tin Fiddle.
There is a factory made aluminum violin for sale right now in the classifieds, although its made to look like wood.