Earlier quoted context omitted.
I can only speak for what I saw done first-hand. Some guys used their own shanks/shivs/whatever you want to call it, basically any old piece of metal. This was obviously done in their cells on their own. Much more frequently [and out in the open] though was guys using the plastic butter "knives" that came in the dinner trays (think KFC, individually wrapped sets of 1 plastic spork, 1 wetnap, and 1 plastic butter knif…
you had bics? like these? http://webcuriosita.it/wp-content/uploads/2018/01/penna-bic.... at school we used those as dices directly, notches on each of their six sides, making them roll in a bunch was random enough.
http://www.bonvan.com/images/up_images/officepen/229.jpg
The end of the piece that sticks out from the cap worked just like a tiny plastic shovel