Never waste the opportunity of using a project as an excuse to buy new tools. A lot of fabrication will be required making racks to hold all of the batteries I plan to use. I will also need to make a mount for the new motor. So, I purchased a MIG welder.
Welders join metal by heating the joint above the melting point of the metal. The heating is done by passing current across an air gap between the joint and the welder tip. An arc is formed, and as the sparks fly, some of the metal is vaporized. The welder replaces this with a filler metal. In the case of a MIG welder, the filler metal is a spool of wire fed through the tip of the welder. An inert gas is sprayed around the metal joint to protect the metal from oxidation while the metal is molten.