Nice tutorial. Do you have maybe a sketch for the top? I mean a theoretically tuned version? Thanks!

Click on the image in Step 6. You can save/print that and use it as a starting template. There are too many variables involved to give a one-size-fits-all answer for a pleasantly tuned instrument (wood itself; thickness; width; chamber size and shape; etc. Some of that is why some instructions speak about the ratio of the tongues, rather than exact measurements. Especially the first time, you have to experiment and learn some fundamentals. Have fun while learning, and make sure it sounds good to you, not just a tuning mechanism. At the end, even if it isn't a great drum, you will have a unique gift box. You will also have much improved skills and knowledge for your next drum.