Related - this insane project to build the "most 3D printed" 3D printer [0]. The author has 3D printed mechanical components, motor windings, and a complicated

Related - this insane project to build the "most 3D printed" 3D printer [0]. The author has 3D printed mechanical components, motor windings, and a complicated electomechanical "motor controller". The whole thing is intended to work from 3D printed punch cards. I'm not sure how much of this project actually works, but it is interesting. 0 - https://clickprintchem.wordpress.com/2022/05/31/self-replicating-3d-printer-year-3-and-4-review/ https://clickprintchem.wordpress.com/2022/05/31/self-replica... I'd probably also pick some kind of "punched" card; a print of some kind with holes in one place and not in another. The presence of a hole could be checked with a bed probe if everything was lined up correctly. I doubt the plastic would be intact for centuries like you want, but it would certainly outlast the printer you use to read it. A paper card would probably last longer though. For high density, your best option is probably microfilm.