Start with the sides and the legs. Make sure the sides are easily long, wide and deep enough to accommodate the screen. Also the raspberry pi, speaker and cabling need to fit in. I cut a recess into the legs to fit them into the sides. Make the section to house the joystick and buttons and attach to the side. Lastly make the top out of 4 pieces such that the hole in the middle is the same as the viewing size of your LCD screen. The sides of the table should be wide enough to sit a wireless keyboard and mouse on it. Route the underside of the top to make a recess to fit the perspex. Route a curve into the inside edge of the top. Attach the top to the legs and sides.