A 20th-century manuscript of codes (including runes) from Iceland: Einkaeign 1 (1928).
I came across this fascinating Icelandic paper manuscript completely by accident, while searching for more digitized medieval manuscripts (e.g. a prayer book, law book, book of romances, and fragment). I have written about post-medieval manuscripts before, but none as young as this one, from 1928! It is still very much a manuscript, written by hand with pen and ink, and is a lovely example of how scribal culture continued to thrive in Iceland for hundreds of years after the Middle Ages. This manuscript also differs from others I have written about in that it does not contain sagas, laws, or other narrative accounts, but codes, including several pages of different types of runes. The images here are representative of some of the different sections in the book.
The title page (photo 1) reads Rún: rúnaletur o[g] fl[eiri] ritað fyrir Magnús Steingrímsson, Hólum í Staðardal 1928 (‘Rune: runic (or, ‘coded’) writing and other things, composed for Magnús Steingrímsson, [of the farmstead] Hólum in Staðardal, 1928’). This indicates the manuscript was commissioned, but it is unclear for what purpose.
The images are from Handrit.is. The full manuscript (114 images) can be seen here: http://handrit.is/en/manuscript/imaging/is/Einkaeign-0001#0000r-FB.