I'm going to pass over the obvious indoor activity.
My previous hobby was Gourd crafting.
I'll get out my wood burner and dreml during spells of wet weather and switch my head to creative mode.
I do fret work using the little circular saw bit.
Weaving using pine needles or other stuff I've gathered.
Burn designs into the surface, free hand or transfer.
Inlay bead work.
They really are a great blank canvas. You're only limited by your imagination.