Casting means using a temporary form as a mould. This can be sand , Aluminum Foil or a Balloon. This is a neat method to use  for molding and  decoration  purposes .It is easy, versatile and fun to use different shapes and sizes and provides plenty of options for the creative spirits. Moulds used for casting are used only once and then discarded  but since the material is so cheap that to discard them once using is not a big deal. The casting method allows you to experiment with and explore the wonderful plasticity of wax