I spent some time with a nephew in Colorado this summer and he gave me some antlers for knife handles. I made him a knife and sheath when I got home using one of his antlers.
The antler was large and I left most of it as he is rather large with big hands. The knife is about 9" overall and should be comfortable for him to use. The sheath has a tapered welt and just a simple border stamp. I believe this is the only thing I've ever made without some carving on it.
He is a dedicated hunter and should get some good use from it.