Looks like you have enough to keep you busy for a while!
Looks like you are using rasps and files. You may know this already, but just in case, when you are working on horn (and wood, too, for that matter), it's a good idea to stop using rasps well before you get near to your final dimension. The teeth of a rasp can bruise the horn (and wood). So stop using the rasp and files earlier than you might think is necessary, and from that point switch to scraping. That will help you avoid having rasp stripes in your final product. (I'm not talking about texture. I'm talking about parallel stripes where stains affect the bruised areas differently than the areas around them. A horn can be bruised and you not even see it until you apply a stain. Same for wood.) You can scrape with a card scraper, or a knife, but I think one of the best for horns is a sharp pair of scissors. (Glass will work, too, but I don't like using it. I've had it break and chip while using it.)
Scrapers on horn will usually leave some tool marks. In my opinion, for "user" horns, small lines or ripples are not something that need to be polished out. I scrape horns as nicely as I can, then I rub them vigorously with wads of the scrapings to burnish them, but I do not polish out all evidence of scraping. The antique horns I own all show some ripples or other tool marks--evidence of being scraped. I find that final scraping is usually smoothest if it is from tip toward the base, as that works with the grain of the horn.
Another tip that you may or may not know, is when you are ready to make and fit the small plugs (spout end), you can use the tang of a file to scrape the inside of the spout hole so as to get a good taper. That's a good taper for a spout hole, so that the spout plug has a fiction fit but doesn't get stuck in damp weather. You can also use a small knife to scrape the spout hole right around the mouth of the spout just a bit more, to make that last 1/4" or so slightly larger in diameter, so that the plug doesn't fit tightly there. That helps keep the plug from cracking the spout as the horn shrinks and swells in the seasons.
Maybe you know this stuff already, but I wanted to share it. Maybe it will be useful to somebody.