BOOK’s man…BOOKS!
A good quality paperback version of something useful.
For fiction and LARPing (that’s you, brig 
) the zombie apocalypse handbook, or something home made with hand written looking notes and coffee stain rings.
For reality, maybe a bush survival guide, SAS handbook (those can come realy small, picked one up at Oxfam size of an old HDD lol)
Paper does not run out of RAM, battery life or get a cracked screen lol.
Just make sure not to break your only pair of glasses, after you become the last person on the planet (just remember to turn off the Sun before you quit the game of life lol)