XP-Pen Star G640 Tablet holder (for osu!)
This is designed specifically for the game osu!. It's used to always have the tablet perfectly at the same spot on your desk as well as unable to slide, so you can reliably train muscle memories, while at the same time being removable (you may need a spudger to get it off) and thus in my opinion better than permanently gluing your tablet onto your desk and more accurate than using velcro.
You need to drill 2 holes in your desk. Put the holder into the position where you want it (best measure that it's perfectly parallel to the front edge of your desk) and then draw a circle through the 2 holes on the top and drill holes at these points. Then you can put the pins through the holes and thus finish the holder. It can then be inserted onto the holes and the G640 tightly fits on top of it, putting it on the exact same spot every time, while still leaving you the possibility to remove and remount it at any time.