A while back, I had a big project that involved making a lot of cases that called for adjustable shelving. While drilling the shelf pin holes, I found that the hardboard and plywood jigs I had made wore out too quickly. And the fancy store-bought metal types can be expensive. To keep the project on track and moving forward, I found an answer that is the best of both worlds: An old aluminum ruler. The first benefit is there’s no layout required. Just drill the holes centered on the spacing you want. I chose 1" intervals. The other advantage is that you can start the series of holes at any inch mark on the ruler.