Thanks for the comments
For this mod, there was no real purpose to take the horse apart other than to show it can be done. I used a 4.8V cordless Dremel ($20 at Walmart). To make it look ad clean as it does, I used a smaller drill bit to start (3/64 bit), then moved my way up to 5/64 and 7/64 until I got the final size of 1/8. As for snugness, it fits perfectly. The viking horn works as well, but due to it being a harder plastic, it it more difficult to remove. I am contemplating trying a black one, but if the nail polish remover discolors the black, I might just end up with a spotted horse
I currently don't have enough unicorn horns to consider selling any at this time.
EDIT: Was told from a reliable and very intelligent person that nail polish remover is a very bad
thing to use. Go Brasso!