It is really simple to make a patch, here's a couple I did years ago. A better pic of the original is in Scott's
Building The Southern Banded Horn under the Kendall collection. I used Pewter as the patch and made pewter pins, the original is Silver. The other was made because I had scrapped the horn to thin, it is Heart shaped and held with a couple of tack.
I have also made patches of soft lead rolled into a 1/8th" or so dowel, this kind of repair would be done with the Butt out or before it is put in. Fit the plug to the hole, you may want to drill the hole out to a little larger size depending on its size and shape and peen the outside end over while supporting the inside piece with a bar. Easier done than typed.
There is another way if you want to play around with it; it involves packing damp sand, if you have ever done sand casting you know what I'm talking about, into the horn, once you can see it at the hole pack about two inches more in, take a wire and dig some of the sand out, clean the out side of the horn around the hole really good with some Alcohol. Then make a dam around the hole with some Bake able modeling clay about the size of a dime, depending on the hole it should cover maybe an 1/8th of an inch around the hole, pour some Lead or Pewter into the hole, remove the clay, you can peen it a little (this whole operation takes some practice) set the horn in the sun to dry and clean out the sand.
Probably more than you wanted to know.
Tim
