This simple design was just what I needed. Was tired of having to set stuff on my charging cables when they weren't being used so that they would not slide down and off of the back of my desk. I made it with three holes in case I want to later add a cable to charge my phone, power an audio interface, or whatever it may be. 

To attach it to my desk, I just used some hot glue and it has held just fine over the past few months.

If you make one, I'd love to see how you're using it!