Metal is one of the most common materials in modern society, and is an absolute must for many large and durable projects. The ability to attach metal objects together is essential skill in the creation of many projects large and small, simple or complex.
If you have never welded before, this is probably where you want to start. MIG (Metal Inert Gas) welding uses a special hand-held gun that used to feed a solid wire electrode and mixture of gasses onto the contact point, fusing the metals together. While not quite as easy as using a hot glue gun, the action is somewhat similar.