Posted by ubiquitous on
URL: https://forum.librecad.org/Line-Width-tp5716645p5716685.html

Not a solution but maybe a workaround.
What would happen if you copied the lines you want over 2.1 mm width and offset the copy by an appropriate amount. Just a fanciful thought.
If that was to work then perhaps a macro to automate the duplication - I am not a programmer, let alone a developer so I have insufficient skills to try this.