I’ve preferred wood and posted wooden whistles from MusiqueMorneaux in the collections on forum.
From South Korea here is a recent video made with a custom blackwood D whistle.
https://www.youtube.com/watch?v=t2LlQ-ehNLU&feature=youtu.be&fbclid=IwAR0G3jV7U23iMozkECjPmNT_ACldrXeXR53DccWXdao_B9Y2sPDF7eKi32Q