huntin dog :
horn can be worked with the same tools as wood and horn even has some grain to it ,,, start by smoothing the entire length of the horn to make it uniform , run a piece of wire down the big end to find where the inside cavity starts mark this on the outside of the horn ,not to be different but don't cut the horn off another 1" down . use as much horn as you have don't waste any of it . square the tip and pray to the red gods that your drill will run straight and true . if that part works ,then its time to lay out the throat , this is done by the golden rule method , PM me and I'll be happy to explain the golden rule method . the rest is filing and scraping . I try and resist the use of sandpaper and buffers ..The most important thing to remember when building a horn is to take your time , and not hurry the job . be prepared to take 20-30 hours to complete !
best of luck , if I can be of any help please let me know , No i'm not and expert by any means but have built a few horns in my day....take that for what its worth !!!!!!!