Home built aircraft can be built out of a variety of materials and the most common material is sheet metal. Sheet metal or metal-monocoque construction offers a lot of advantages for the construction or aircraft primarily that it is well suited to mass production. In the homebuilt market metal construction is the most common method of building an aircraft primarily because of the enormous popularity of the RV series of aircraft. Homebuilders also use metal because it is the most durable material available.
Metal is an excellent material for building aircraft, because it is so strong aircraft can be built out of thin sheets of metal keeping the weight quite low. It really is amazing how a flimsy sheet of metal can become incredibly strong just by changing its shape and inserting a few rivets. The metal of choice for most aircraft is aluminium, primarily because of its excellent strength to weight ratio.
Almost all certified airplanes are built using sheet metal, primarily because it is well suited to mass construction. Metal aircraft are also the most common homebuilt aircraft because they offer a number of advantages to the homebuilder. Probably the biggest advantage is the durability of metal aircraft, they have no restrictions on exposure to the elements like composite or wood airplanes do. They are also safer than composite airplanes in the event of a crash. They are also much easier to repair than wood or composite aircraft in the event of damage. Other advantages of metal is that it is relatively easy to work with, it is not temperature sensitive so your work shop doesn't need to be climate controlled, no harmful chemicals are used, and few people have allergies to metal.
The biggest disadvantage of metal airplanes is that they can't shaped into complex shapes like composites can be. This limit's the kinds of designs that can be built using metal construction. Another disadvantage of metal construction is that it can be quite tedious. There are a lot of rivets involved in building a metal airplane making the work very repetitive. There are also a lot of sharp edges when using metals, you will cut yourself.
Metal-moncoque construction has many advantages but like any material it also has its disadvantages. There is no such thing as the perfect material for building an aircraft, everything is a compromise. It is important that you do your research in order to ensure that you choose the best construction material for your homebuilt aircraft.