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I had to select a solid cylinder, then select a second solid cylinder, then use the alignment tool, then the subtract function to create a tube. Is there a way to add primitives such as a tube to the current library for future use? A threaded rod or an inside thread such as the one inside a nut would be helpful as well. I know that I could create my own library, save it on my computer then import it but I'm looking for a way to integrate it into the program.