If you have ever tried cutting miters on the tablesaw using a stock miter gauge, you know how dicey it can be to get accurate 45° cuts. And if a cut is off by even a degree, the error doubles when the mitered piece is paired with its mate, creating a “square” corner that is anything but. Miters cut this way often have to be trued afterward, typically using a hand plane and shooting board. Fortunately, there’s an easier way: using this dedicated miter sled. The jig is foolproof due to its two fixed fences which are set squarely to each other and at 45° to the blade. Just position the mating workpieces against the adjacent fences in their assembled relationship for perfect 90° frame miter joints every time. The rails at the front and rear edges keep the sled panel flat, which is important to prevent twisted frames. I used 9-ply 1⁄2"-thick hardwood plywood for its stability. If you’re willing to invest an hour or two building this sled, the time will be paid back in spades with no-fuss miter cuts that are ready to go right off the saw.