Created a board mount using FreeCAD (1.x) so that it could be parametric.  The mount uses bottom mounts sized to fit the screw and the board to mount and a top to keep it stable.  The top can also be used to easily pop off the board so it could be taken down and put back up without much effort. 

Hope you like it! 

Be kind, this was my first FreeCAD design, while very similar to other CAD tools, it is somewhat different.  

The git repo for the model is here https://github.com/wedgen/scad/blob/main/hooks/u-bracket.FCStd I'll try to update on this post also.