Make a sketch design of the rack case to guide you. Cut two plywood boards measuring 1 by 2 feet for the top and bottom of the box. Then cut eight plywood pieces: four pieces measuring ½ by 1 foot and the other four measuring ½ by 2 feet. Plane all the sharp edges to make them smooth.
Cut 16 pieces of perforated aluminum strip: four measuring 2 feet each, four measuring 1 foot each, and eight measuring ½ foot each. Join the plywood pieces using perforated aluminum strips, spring nuts and a screw driver to the corresponding plywood measurements.
Place the top portion of the case on the bottom portion to resemble a closed rectangular box. Mark the front part, fix the handle, and lock clasp using spring nuts and the screw driver. Then mark two other points at the back of the "box"; 1 ½ feet each from the corners and fix the hinges using spring nuts and the screw driver.
Put the music mixer inside the "box", draw its outline and apply glue "outside" the outlined area. Partition the inside of the "box" leaving only the space where the mixer will sit using the sound proof soft padding material. Cover all the remaining spaces, filling it up with the soft padding sponge to cushion the music mixer.
Apply glue to the outside surface area of the "box" and cover with a thick carpet material. Cut off any excess materials and confirm that the box can open and close easily.