Chorder

I am a musician/producer, and when working by myself in the studio, I often need to have a chord held down on a keyboard while I go over and make adjustments. This is a 3D printed item that helps out with that.
You just place it on the keyboard and place a weight on top of it (a guitar pedal like the one in the picture is the right size and weight), and a chord of white keys will be held down. The part also has tabs on the outer sections so that, if the keyboard is tilted toward the player, it won't slide off.