Be the envy of every halfling rogue from here to the West Marches! These'll be so cool that you'll have to make tons because they will disappear from the table. Maybe fairies or something.
Just search and replace the font name (in this case, it's 'Duvall') with a font that is registered in your OpenSCAD, render, export, and BOOM, Critical Hit!
Note: this does not enable the file to make the final step into the Prime Material Plane: only a Limited Wish or other reality-bending, sanity-blasting magic, or possibly a low-end 3d printer, could do that!