can sketch free make individual building pieces showing joinery bits then fit it all together, like a exploded view them show in 3D view?
absolutely, by using components, tags and scenes.
Your individual building pieces would be the components, copied on 2 tags (for example), one being the exploded state the other one the 3D view of your general object.
the scenes then save the tags visibility setting and allow you to toggle between the two states
Thank you ill give it a try.