A Tagua nut the size of a medium lemon is pretty large...most that I get are a bit smaller. It is perfectly possible to get some pieces the size of Guitar saddles or nut...or tuning pegs...out of some. The limiting factor is the angle and shape of the hollow place in the center where the nut's growth occurs if they aren't harvested and dried.

Here's what I do with them the tallest is about 1½ inches.