Could you make them from naturally shed antlers?
I have some beautiful knives with elk handles that require similar care - which is easy since it’s wise to oil the HC steel as well - and they’ve survived many camping trips in inclement weather. Granted it isn’t technically vegan since it is an animal product, but since it’s gathered after being discarded in the wild, it’s about as close as you can get with no worries about animal ranches or slaughtering for the horns.
