DIY Floating Shelf with Hidden Storage

Sponsored by Imbot

Build a clean, minimalist floating shelf with mitered edges and a hidden wall-mounting support frame. Thank you to Imbot for partnering with me to provide this free woodworking plan.

Materials & Tools

Tools

Supplies

Parts Diagram

Outer Shell (3/4" Plywood)

Note: All dimensions measured along the long outer edge of 45° cuts.

  • Part C (Front): 1 piece — 4.5" × 24" (All 4 edges cut at 45° inward)
  • Part A (Top & Bottom): 2 pieces — 24" × 8" (One 24" edge cut straight at 90°; remaining 3 edges cut at 45° inward)
  • Part B (Sides): 2 pieces — 4.5" × 8" (One 4.5" edge cut straight at 90°; remaining 3 edges cut at 45° inward) 

Internal Support Frame (1×3 Nominal Lumber / Actual 0.75" × 2.5")

  • Parts D (Front & Back Rails): 2 pieces — 22.25" long (90° square cuts)
  • Parts E (Side Ends): 2 pieces — 5.5" long (90° square cuts)

Frame Bottom Plate (1/4" Plywood)

  • Part F: 1 piece — 7" × 22.25"
🛠️ View assembly animation
Exploded view showing how the parts fit together

Part Diagram

Step-by-Step Instructions

Step 1: Lay Out and Tape the Outer Shell

  1. Lay Parts A, B, and C face-up (outside faces facing up) on a flat work surface.
  2. Arrange the pieces into a cross shape centered on Part C. Ensure all mitered edges touch seamlessly, with the 90° straight cut edges aligned to form the open front of the box.
  3. Apply painter’s tape firmly across all joining seams (shown in blue). Use a rubber roller or block to press the tape down securely.

Step 2: Fold and Glue the Box

  1. Carefully flip the assembly over so the taped side rests against your workbench. (Tip: Lift by the center piece Part C, allowing the sides to drop naturally into a box shape as you flip.)
  2. Apply wood glue generously along all 45° mitered edges (highlighted in green).
  3. Fold the sides up to form the box, pulling the joints tight and securing them with additional painter's tape across every seam.
    🛠️ View assembly animation
  4. Optional: Drive 18-gauge brad nails through the corners for extra strength. Note: Only recommended if painting or using a dark stain, as nail holes will remain visible under light stains.
  5. Allow the glue to cure fully according to the manufacturer's directions.

Step 3: Build the Internal Support Frame

  1. Position Parts E between the ends of Parts D to form a rectangular box frame.
  2. Apply wood glue to the ends of Parts E, clamp, and pre-drill pilot holes through the face of D into E. Secure using 1-1/2" wood screws.
  3. Apply wood glue along one 3/4" edge face of the assembled frame (shown in green). Place Part F flat on top, aligning the edges.
  4. Pre-drill pilot holes and secure Part F to the frame using 3/4" wood screws.

Step 4: Sand and Finish

  1. Once the box glue is fully cured, remove all painter's tape.
  2. Sand all exterior surfaces of the main box using 120-grit sandpaper, followed by 220-grit for a smooth finish.
  3. Wipe away dust and apply your choice of stain and clear coat (polyurethane) or paint.

Step 5: Wall Mounting and Final Setup

  1. Locate the wall studs where you plan to mount the shelf.
  2. Position the internal frame against the wall with one D part against the wall. Ensure the frame is level. Part F should be on the bottom of the frame.
  3. Drive 3" wood screws through Part D of the frame directly into the wall studs.
  4. Slide the finished outer box shell onto the mounted frame.
  5. Optional Locking Screw: Drill a small pilot hole through the bottom of the outer box (Part A) into the support frame (Part D). Insert a 3/4" screw to lock the shelf in place and prevent it from sliding off accidentally.