Summary I needed a very strong and small worm screw + gear kit... I worked very hard to succeed, if I can make you benefit! It is because when you print a small worm gear horizontally, the teeth are fragile, and when you print it vertically, it is the main shaft that gets fragile. So I had an idea... I designed the worm with a hole so you add a metal screw in the middle. Instructions I print the worm screw very slow. half usual speed. I print every thing with 100% filling. I print the worm screw and the gear with concentric filling pattern. No support material. My desing is made to add a 2-1/2" 8-32 bolt. Before to get the metal screw in the hole, you can fix it with a drill and a drill bit. Then put a Iot of abs plumber's glue on it, it helps by lubrificating and once dryed it is stronger. When it is dryed, I suggest to put the worm screw in a drill and use folded sand paper to make the worm smoother. Then you can assemble every thing and you can glue the worm stopper. N.B. On one picture, you can see the fittings for my specific needs. I removed them on the stl file so that you can customize it as needed. I suggest to add some bearing grease to prevent heat and melting.