What I think you see are a couple icon. In tools-customize-sketcher there are additional tools that can be added to the standard toolbars, I have shown what the icons look like. These tools are used in the 3D window, I think you click on a sketch and then click mirror and FreeCAD creates a new sketch, you can then select 2 sketches and merge. I'm not sure of the whole proceedure to get to a full solid mirror/swap of your text.
Last edited by freedman
on Sun Mar 29, 2020 4:33 am, edited 1 time in total.