There are two common methods for creating an object capable of flight. The first involves a craft that has a density lighter than air. This allows the object to float in the atmosphere. The second form of flight focuses on the use of thrust to propel an object through the air.
The common balloon is the simplest example of a lighter-than-air object. A balloon filled with a low-density gas such as helium or hydrogen either hovers or rises. The altitude of the balloon can be controlled by adding or subtracting weight.
The second method mentioned is the kind used by birds, insects, planes, rockets and helicopters. There are a variety of ways for a flying object to produce thrust. Animals create thrust by beating their wings to cause lift. This process can be duplicated mechanically, but most flying objects rely on motorized propellers or jet engines.
A homemade flying device utilizes any one or a combination of these methods. The form chosen depends on the wishes of the inventor. A small electric motor paired with a battery potentially powers several different styles of craft. There are also numerous small rocket engines available in retail outlets. Control could be maintained by radio contact or a guide wire.