The scale is generated from the numbers at a 1.000 mm pitch and the scene is built in millimetres, so the model is exact. What is left is your printer: check your flow and your XY calibration once against the printed ruler and it will match. Any shrinkage in the print shows up here honestly rather than being hidden.

Built and tested on 4.0 and 3.6. It uses nothing newer than Blender 3.6, and it ships a manifest so 4.2 and later install it as an extension. If a version between those gives you trouble, tell me and I will fix it.

The 3MF is written in the Bambu Studio project flavour and I test it there. Orca reads the same package and keeps the parts. PrusaSlicer and Cura open the geometry; they ignore the project settings block, which is why the layer numbers are printed in the documentation too. I have not print-tested every one of those slicers myself yet. The day I do, I will say so here.

No. With one extruder you insert a filament change at the two layers the build report names. With an AMS or a toolchanger the parts are already assigned to their filaments. And the see-through lettering needs no second colour at all.

Yes. Text is ordinary Blender text, so any font Blender can load works. Vector artwork comes in through Blender's SVG importer and is scaled to the width you ask for. Raster logos are used for reading the brand colours, not as artwork.

Two pieces of artwork are touching at exactly one point, most often two letters of a word. Slicers handle it, so the print is fine either way. To remove it, nudge the pieces apart or add a little tracking to the text and build again.

Yes. The cards you design and print are yours, with no restriction and no attribution. The add-on itself is GPL, so if you redistribute a modified copy of the add-on, that copy stays GPL.

Never. It makes no network calls, collects nothing and phones nowhere. Install the zip and it works on a machine that has never been online. Updates and support are included for good — no support period, no renewal fee.