Creating any project from scratch can be a hassle, especially if most of your projects need to be the same dimensions every time. Andy Fogarty,The At Home Welder, created a video to help welders make reusable welding jigs. These jigs can be used for any welding project you want, but he created the jig for down rails. The video tutorial is very detailed and takes you through all the steps necessary to create a reusable welding jig.
Have you made a welding jig before? What projects have you used it on?