"Methods of making practically invisible changes to pure text are available too" as mentioned in the post referred to. If using printer fonts rather than explicit vectors then it is possible to hide enough data in small "mistakes" invisible to the naked eye.
I'm not sure what would be possible for pure vector graphics.
For vector graphics, I suppose you could encode information in the least-significant bits (with redundancy, error correction and whatnot) if the printer can guarantee sufficiently high precision (not accuracy, mind you: https://www.tutelman.com/golf/measure/precision.php)
I'm not sure what would be possible for pure vector graphics.