I think I picked this tip up on the metal meet forum (I can't remember the guy's name so I can't take credit for it - I can take credit for the wonderful art work however!)
It has turned out to be quite useful for metal shaping recently.
It is just a lump of tropical hardwood I saved from an old window frame shaped into a bat with a handle. A leather belt has been stretched round the nose to provide a bit of cushioning.
The point of this bat is to help with (very) rough sheet metal formation. The addition of the leather belt helps to iron out your mistakes and poorly aimed blows!