Hello , looking to build a helva hammer

[LastResort]

I'm Daniel ,live in VA , have been fixing / making things for years. I just got David Gardiner's DVD , and for years have wanted the ability to shape / form sheet metal. I do work full time as a mechanic , I did work at a "Hot Rod " shop that closed up , and restore car's fab parts and make things? I have a mill lathe MIG & TIG acetylene home made air powered brake , Polishing things on my made machine. I have watched a few vid's of a helva hammer , seems like something use full ,this is the place to find out how?
Thanks