I just got these 1/4" gripper pads in the mail and tried them out. These were meant for furniture so its thicker than I expected.

I wanted something that would fit in here so those round ones wouldn't work well.

I cut them to the size I want and they hold very well. Keyboard wont budge. Behold the levitating keyboard!

To be fair the keyboard weighs 4.5 lbs to begin with but I didn't want to scratch up my desk. So.....

I have clear round ones coming in the mail so gonna give those a try too. lol