The reference specimen for the horn shape and size were the Sassenberg, Berlin, London and Baikal specimen. I checked each millimeter, so the dimensions should be correct. At first, I sculpted the bony cores as they are in the original skulls. I started by adding wire of the right size and curvature:
Then, I started to sculpt the "horn core":
|If you look at fossil skulls, I would say those horns turned out to be very accurate|
Then, I added the horn tips which would add about 30% to the length (average, but there is great variation) by following the curvature:
After that, I added the thickness of the sheath. As original aurochs horn sheaths are known to have added about 1-2cm in thickness to the bony core, it would be about 2-3mm in the model, which is what I did:
Then, I completed the shape:
And sanded it with sandpaper:
The result resembles the horns of wild yak greatly, which have horns nearly identical to those of aurochs. I think about adding a bit to the thickness of the horns, looking at live yaks and preserved horn sheaths.
This is what the (nearly) finished model looks like at the moment. I will start painting it as soon as I can:
The head and horns look a bit huge due to perspective, by the way.