This project was designed by zenziwerken https://www.thingiverse.com/thing:3053615 and was supposed to be used for 18mm material. I only had 15mm material in my shop and made the project file to fit my requirements. I used 15.5 mm plywood and it doesnt matter the tool size as long as you select outside for the cutting and inside for the pocket. Pocket size should be about 10mm depth. Here is a video of how i made this project. Enjoy.