Ledge stone stacks like bricks, but the stones are uneven in shape. Using the redwood guide from above, stack two layers of ledge stone as wide as the steps. Rearrange the stones until they fit well together. Use the same process to dry-fit the stones for the other steps.
Starting with the bottom step, carefully set aside the stones, making sure to keep them in the right order. Use a drill with a paddle bit to mix mortar to the manufacturer's specifications; it should be the consistency of brownie mix. Spread a layer of mortar along the front edge of the step as a base, then set the first layer of stones on top of the mortar, spreading mortar in between each stone. Use mortar to set the second layer of stones on top of the first. Check the stone facing with a level, adding or removing mortar as needed to level the structure. Use a wet sponge to wipe away excess mortar from the front of the facing. Repeat for the other facings.
Measure and cut three lengths of 4x4 redwood lumber for the step frames. For each step, one piece should be the same length as the step's width (the same as the width of the stone facing). The other two lengths should measure the same as the depth of the step from the front of the stone to the soil at the back.
Lay out the lumber for one step frame; the shape should resemble a box with one side missing. Drill holes slightly narrower than the width of the 4-inch bolts, then use a mallet or hammer to drive the bolts through the holes to connect the pieces. Once the frame is assembled, drill 1/2-inch holes from top to bottom through the side pieces to accommodate the rebar supports. Repeat for the other frames.
Spread a layer of mortar on top of the ledge stone facing. Protect the edge of the redwood frame with tape to prevent staining and set the frame on top of the facing. Check for level, adding or removing mortar as needed to level the frame. Use a small sledgehammer or a heavy-duty hammer or mallet to drive the 2-foot lengths of 1/2-inch rebar through the holes in the frame and into the ground until they sit flush with the top of the wood. Repeat for the other frames.
Fill in the bottom of the steps with mortar until it reaches the bottom of the redwood frame on both sides. Create a mound of mortar behind the ledge stone facing to support it.
Let the mortar dry, then fill in the steps with crushed rock up to the top of the redwood frame. Wet the crushed rock with a hose and tamp each step with a post or tamper. Add more crush rock to the top of each step.