Some wood carving tools, and a wood burner or ink. Get some branches or saplings, cut them in equal sizes and make sure their girth are somewhat similar. You can scrape away at the bark, then carve or write with ink, or both the symbol of choice.
You could also carve the symbols on the tops, and look for sticks or branches that have larger girth, and cut them slim, so you can write on the insides the symbols.
and acorns and other wooden shapes (I guess you could use actual acorns as well! Now there's an idea.)