Does there exist a tool like Paperback for Linux?
PaperBack is a free application that allows you to back up your precious files on the ordinary paper in the form of the oversized bitmaps. If you have a good laser printer with the 600 dpi resolution, you can save up to 500,000 bytes of uncompressed data on the single A4/Letter sheet. Integrated packer allows for much better data density - up to 3,000,000+ (three megabytes) of C code per page.
That is, something that can represent more data than e.g. QR codes, and can be printed on paper?