I wanted a way to hang a HP Thin client off the back of a monitor.  I stated with a basic VESA mount I found here .   From there I added some material and sliding dovetail connector.

It has mounting holes spaced at 100mm & 75mm.  

Print Settings

Printer: Creality Ender 3 Pro

Supports: Yes

Resolution: 0.20

Infill: 25% Cubic

Filament: Amazon Essentials Red PLA