Square bracket for monitor arm VESA

Remix of the piece "35mm_tube_mount.stl" for adaptation on 20mm square extrusion.
Use a screw M6 X 20 or M6 x 30
Rev. 1 :
- Before square int. : 20mm x 20mm
- New square int. : 20.8mm x 20.8mm

You can view ans export 3D : https://cad.onshape.com/documents/fa49455fe6a52af6af6dc61f/w/09edaa0e32104cb4cac84511/e/8a9bd58dfe42ee0eb1d223be


Remixed from https://www.thingiverse.com/thing:2700618