I designed this for my YESHOMY Height Adjustable Electric Standing Desk, the top measures 15.25mm thick.  It lifts my Bose Companion 2 Series III speakers to be inline with my monitor, but mostly it just frees up a little visual desk space.  The Fusion 360 file is included so you can easily modify it to fit your own speakers or preferences.  I ended up adding a piece of double sided tape to the back of each piece so it wouldn't slide around.