Step 1: Parts Layout
Step 2: Assemble box, lay out wrenches
assemble the box using wood screws trough the ends of overlapping wood. If the large lengths of wood are too unwieldy, you can use small pieces of plywood on the corners to attach the larger piees of to each other.
Step 3: Nail into box, suspend wrenches
Between each pair of nails is a wrench, suspended by a length of string on each side. Experiment with string tension to get the sound you want out of each wrench