You could always try making a sheath out of birch bark, as a conversation piece - I made one for an Erikson Mora knife last summer and I like it better than the original black plastic one. (Although it was a first attempt and not very well made, it seems to hold the knife more securely.)

IIRC, Mors Kochanski's "Bushcraft" (aka "Northern Bushcraft") has a section on crafting that describes how to make one.