Clamp the 4x4 to your work surface. Using a pull saw, begin by notching the front corner at the 45-degree angle, then notch into the marked angle at the corresponding back corner. Level the blade of the pull saw across the top of the block, connecting the two notches with the saw blade. Cut away the V-shaped channels running through the crown following the 45-degree cut lines. Turn the 4x4 a quarter turn and repeat this process on the perpendicular axis. Once the cuts are complete, the intersecting V channels will create 3-dimensional triangles atop the block.