Parametric breathing mask buckle

There are several breathing mask buckles out there, but none of them were the right size for the masks my wife is sewing. These buckles are used to hold the mask in place, without having to wrap the elastic bands around your ears.

This is inspired by the buckle the Creality3DPrinter folks originally published here https://www.thingiverse.com/thing:4187448
and by the remix ubidefeo published here. https://www.thingiverse.com/thing:4231024
Customizing with OpenSCAD is probably easier for people not familiar with visual CAD programs.