Place one of the sheets of plywood onto your work surface, and place the mixer on top of it. Draw an outline around the mixer using a pencil, remembering to leave additional space for power cables at the rear panel. This will save you from having to completely remove the mixer from the case each time you wish to use it.
Draw another box around the mixer outline, roughly half an inch larger than the first. This will allow space for the protective foam.
Stand another sheet of plywood on its edge next to the mixer, parallel to its side panel. Mark the dimensions of the mixer, adding extra space to accommodate the protective foam and the mixer's knobs and faders. Repeat the process with the front panel of the mixer.
Cut out the base, side and front pieces, then place each one on a blank sheet of plywood and draw around each one to create a duplicate. These will form the top, side and back pieces.
Use the Phillips head screws to attach the front panel to the top piece at a right angle.
Place the base on your work surface, and screw the back panel to it using the Phillips head screws.
Screw the left and right side panels to the base piece, and add additional screws to secure each one to the back panel, creating a base with three side walls. The fourth wall is attached to the lid and will slot into place when the lid is closed.
Screw the breakaway hinges to the back panel and the top panel, at the point where the two panels meet. This will form a lid that covers the controls when fitted, but can be lifted off completely when opened. This will allow you to operate the mixer without having to fully remove it from the box.
Screw the two halves of the case clasp to the front panel and base.
Cut pieces of foam to size in order to fit the inner surfaces of the box.
Paste glue liberally inside the box and fit the foam. Allow it to dry thoroughly before inserting the mixer.