A History of the Gemshorn by Hall Train
"The first tangible evidence of a gemshorn was found in the twentieth century, in the remains of a fourteenth-century house in Germany. This particular instrument was in fact made of clay, but descriptions from the period indicate these instruments were usually made from animal horns. There exist images spanning two hundred years of gemshorns from the 14th to 16th centuries..."
A Rough Guide by Hall Train
"Rather than ordering a gemshorn online, it is entirely possible to make your own, although at first it can be frustrating.
But after making one successfully, it’s hard to stop.
My first couple of gemshorns, while not disasters, were things I was reluctant to play in front of friends and family. My fifth gemshorn was actually made from a curved, I mean quite curved, ram's horn.
I would have made a gemshorn from a ram much earlier had I known it was possible. I grew up next to my uncle's sheep farm. Unlike a ram, the instrument is kind of quiet, and it is great for nocturnal practice..."