For this ratchet design, you will need:

• 1/8" plywood, 150 mm x 300 mm
• 1/4" dowel rod, 45 mm long
• Four bolts, 3 mm x 20 mm
• Two wood screws, #4 x 1/2"
• Four nuts, 3 mm
• Small spring (this example uses a click pen's spring, 3/16" diameter)
• Wood glue
• Small clamps
• Small screwdriver