KC R2 Builders group held a panel on the how to create Star Wars Droids. Their group is a part of a national group of Droid or R2 Builders around the country. They are there to help support members as they build their own droids.
There are free plans out there on how to create your own R2D2. There are plans out there for other types of Star Wars droid but often those do cost a fee.
There was a long discussion of the different options and materials one could use to create their own droids. Some people will print 3-D print their own parts for the droids. Others have used Wood. Aluminum is a wonderful substance to create a droid but it is an expensive substance. Many people will mix and the different materials.
Since 1977, I have dreamed of owning my own R2D2. This is so KOOL! If I had the time and money and patients and ability, I would so build one. I want my own. Check out their site for more information.