I do not have a 3d printer,but Moi3d always shows me if my objects are solid or joined surfaces.Never failed me.This kind of starwars was designed so you can assemble or disassemble your parts.I was used boolean difference operation to make holes.What I am not sure about,should I export my STL or OBJ files like on top or bottom image?

Thank You in advance for advice from people who are skillful with 3d printing :)