Simple method for constructing a worm gear

Here’s a neat idea by telescope maker AstroNutRex: you can make a worm gear by bending some pieces of threaded nylon rod around a circular form. A threaded metal rod is then used as the worm. The resulting contraption probably won’t stand up to heavy loads, however the much reduced gear ratio should be perfect for making minute adjustments to the alignment of large objects such as telescopes. [thanks, David!]