I attempted to create a tube piece having a hole in its side with solid subtraction of a bar from the tube. This failed as neither was recognised as a solid.
It turns out my cylinders from which I created the tube appear to be not solid. The help states an entity is solid if the entity window shows a volume. This is not the case for a pushed circle or a pushed extended circle having the inner area removed (creating a tube by look immediately). As my pushed circle isn’t a solid, I can’t create a tube by subtracting a cylinder having small radius from a cylinder having a bigger radius either.
Thus I ask for help here. Attached the saved circle from which I started all: home.skp (107.8 KB)