~ A little Kaname Tosen headcanon ~
According to the Can't Fear Your Own World novel which Kubo supervised, the Seireitei Bulletin was a one page publication printed off a wooden block like the Edo period publication, until Tosen became captain.
He adopted printing methods from the world of the living which makes me think that he was a soul who lived in the modern world and came to soul society after dying. He retained his memories and experiences, using them to modernize printing and publications in the soul society. (Well, seireitei mainly. According to the novel, the rukongai receives copies of the Bulletin on special occasion only.)
Or maybe he simply is a WOTL guru, saw it once while deployed there and thought how much easier paper printing produces journals and announcements.
On another noter, I think Tosen must have asked Mayuri and the departement of research to develop printers for him and provide them with ink. And I think Mayuri was very happy with the development.
