Before it is hammered, the end of a rivet should stick out slightly more than its own diameter. This will give you enough metal to form a solid head. – Mike Bauer, sheet metal worker
A cool tool is anything useful that is superior to comparable items. If you think this tool is inferior suggest a better one. You are welcome to insult a tool, but comments containing insults to individual people will be deleted. Corrections of fact are always welcomed, if stated politely. Recommendations of better tools are dearly wanted and may be elevated to the front page.