Step 3: Support
We need to add wood inside so there’s something to mount the joystick parts on. There are a number of ways to do this, but the most reliable and easy way is to have a big 1-inch thick piece of MDF in the middle. It doesn’t have to be a perfect fit. Glue smaller pieces of wood directly to the inside of the frame to support the larger piece going across the middle.
Once you have all the wood cut, glue in the supports. Instead of marking where to glue them, just flip your frame upside down (choose the nicer side to be the top) and put in your plastic, followed by the top piece of wood, followed by the side support pieces. This way, the side supports will be at just the right place. Glue in the side supports with wood glue.