Screw thread

No.503526 ViewReplyOriginalReport
How would I go about making a working screw thread for 3D printing? The inside one is easy, just attaching a helix to a tube, but the outside is hard since I can't see a way to inverse a helix inside out. Some chick paid me to make this toothbrush that has the paste in it's handle (don't ask) and I solved this problem by making a 4-sided helix and making the outside one a lot larger, but what would be a better way of doing this? Using Maya.