Pencil in a circle on the center of the 36-by-36 inch piece of plywood with the use of the compass. Evenly separate the circle into six different parts. These will be where the sockets for the tripod will go.
Drill holes into the 12-by-24 inch sheets of plywood with the use of a one inch drill bit and key hole saw. These will act as handle holes on the box for the camera operator. Sand the holes down after you have drilled them in.
Screw and glue the 12-by-24 inch sheets together to form the operator box. Use the strong glue and drywall screws to do this. Assemble the sheets so that the seat is seat is 12 inches wide.
Attach the box ends to the box. Allow the box ends to extend below the bottom of the box, allowing it to be securely attached by drills or clamps.
Drill holes into the three 4-by-14 inch sheets. These will act as your tripod socket sheets. Drill the holes so that the legs of your tripod fit securely. Attach these to the platform.
Sand, stain and varnish your platform dolly. Attach the skateboard wheels and trucks. If you would like, you can also attach a handle to the back of the dolly.