Corner back massager

Every morning in the office, I would notice at least one person rubbing their back on a metal pole running from the ceiling to the floor. I figured if I took a ball, and cut a corner into it, I could stick it to the pole and allow people to really target a portion of their back when they lean up against it. It's been 4 month now and I've added a two others at different heights to get shoulders and lower back, it seems to be a pretty good idea from what people have told me.