If your dead set on antler for a powder measure. The short time it takes to drill/dremmel one out isn't worth the expense to buy, as they sell from $15 - $40 and up.
You can make one out of bone (turkey or deer)or out of a piece of copper/brass with the end squeezed closed. I've made them out of a small gourd tip as well (these can break easily).
My boy made one out of a wood needle case, the possibilities are endless.
I've seen them on ebay (look under blackpowder or antler), there's usually a few advertised there.
If you need to adjust the size, just melt wax into the measurer. Works for me :results: