A very simple hook for a specific purpose.

I have a  shelf in my shower the glass of which is 8.5mm thick and offset from the wall by 7mm. 

This hook was made by drawing the shape in Adobe Illustrator, exporting it into FreeCad and extruding it by the width that I needed. I created two extrusion widths of 5mm and 7mm as I had 2 things that I needed hooks for. 7mm is the maximum extrusion as it wouldn't be possible to push the hook up behind the glass and rotate it into position if it was wider.

It's not “parametric” as such, but because it's extruded I have included the FreeCad file so you can adjust the width if you need to.