Another Shelf HeadPhone Hook

I should have looked for hooks here before I made these.

First one fits a 25mm shelf from the back.
Second fits a 16mm Shelf with nub centered at a 26mm depth.
His desk used to have CD holder slots that I removed.

On a side note, that makes me wonder if the kids that are born in 2013/14 are even going to know what music CDs are. None of my Laptops or PCs even have a CD/DVD player...

Anyway. I may get around to putting the first one in openscad so that the shelf thickness is adju