The ranges of suitable handles for thumb walking sticks are wood, antler, horn even nylon can be used to good effect. I have seen a V handle for one tree and a shank from the type of tree and then jointed together with a collar or spacer covering the joint made from antler to make excellent walking sticks. Antlers themselves can make a suitable V handle that can be trimmed and fitted any shank. Those from roe deer make lightweight walking sticks while red deer make more robust walking sticks with a much more heavy handle.
Next step for your walking sticks - when the antler has been trimmed then the trimmed tines have to be capped with a horn or antler. Buffalo horn is a attractive cap, when the cap has been fitted to the tines its then has to be trimmed and fitted to the antler. Once this is done you can then drill the shank and handle to fit each other an place a threaded bar into the handle first, if you want your walking sticks to stand out before you join the handle and shank together you can place a spacer or collar in between, its simple just drill the spacer the same as the handle and the shank and then place all together, the handle spacer and shank, I like to fit the spacer after you glue the joints. Then you simple spacer and caps have transformed your walking stick, and the same can be done to all your walking sticks.