My logic here is that if pith causes splits in green wood, remove the pith & problem is solved. I’m also only about 2 years into this, and am a slow learner. In pursuit of the mythical non-splitting green wood, I present this experiment for your judgement.
Fresh, green as heck white oak branch. Pen cup resulted, turned about 15cm long, about 5-7cm across, walls about 4-6mm thick. With the pith hollowed out of the bulk of it, should be less prone to split. Just to be sure, I also cored out about a 2cm hole all the way through the bottom, leaving a lip to set a small disc on later. It’s in front of the fan, disc not in place, 35-40% humidity, at basement temperature for the next week or so.
Split or no split?
Place your bets.