A contour gauge is a simple, but smart tool that will make your life as a shoemaker a lot easier. You can buy it at a DIY store and its normal purpose is to copy angles. I use it to mirror-copy 3D surfaces of all sorts, like heels and lasts. The images with the lasts show a modification at the back of the last. The first image shows the original last. The second image shows the modified back of the last, with the contour gauge which still has its original shape. The third image shows the new shape after modification. A new contour is made with the contour gauge which can be used as a guide to shape the back of the second last. The images with the heel show how the contour gauge can be used to mirror the left side and the right side of a heel. When you like this tip, please feel free to share.