I was asked for some details about hardtail horns so I thought I would start a thread with pictures and a life-size template.
You may have to do some photo-shop magic yourself to get it to lifesize. Hope this helps.
It's made of 2mm steel.
If you need the actual horn bit, just search "Mitsuba 6V Horn" on the world famous auction site, and you'll find them with the wrong bracket, they should be about AU$25-AU$40 from anywhere in Asia.