Attach French Cleat Backing

What happens here

Take another 3.5-inch wide plywood strip (from Step 1) and apply wood glue to one side. Position this strip along the back edge of the U-shaped shelf frame, but make sure to leave a precise 0.5-inch gap at the top edge. This gap is crucial for accommodating the French cleat and allowing the shelf to sit perfectly flush against the wall. Clamp this back piece securely until the glue dries. The video highlights the importance of this gap for proper wall mounting and anti-tip stability.

Goal: Once the U-shaped frame is dry, attach a 3.5-inch wide plywood strip to the back, leaving a 0.5-inch gap at the top. This gap will house one half of the French cleat, ensuring the shelf sits flush against the wall.