I'm fascinated by this as a problem. I had an idea how to solve it. Books are not contraband and you can pick two random words from, say the Catcher in the Ry

I'm fascinated by this as a problem. I had an idea how to solve it. Books are not contraband and you can pick two random words from, say the Catcher in the Rye or to name a less controversial book, the Bible and use the first letter of each one to "roll the die". Wrote a small script that tries to balance the odds given the frequency of first letters of words in the English language (odds taken from [1]). Script can be found on Gist [2]. This can of course be adapted to provide tables for common probabilities (say 3d6 for example). All of the methods the prisoners are using is "good enough". Having a table that is not accurately 5% for each number should not be a problem. It will depend on the books used as well. Sample output: a b c d e f g h i j k l m n o p q r s t u v w x y z a 6 15 14 16 18 4 12 16 11 5 7 13 9 3 7 1 11 9 5 2 4 16 20 13 20 20 b 18 13 5 16 3 13 8 5 20 1 15 18 20 20 6 12 3 9 2 15 11 3 9 1 13 14 c 18 10 12 6 1 18 1 1 11 11 8 15 14 20 20 19 19 17 17 19 17 10 1 4 7 10 d 13 6 3 10 17 15 10 12 6 15 20 2 11 1 8 3 3 7 11 19 6 3 13 2 8 17 e 1 4 12 19 17 12 13 6 3 15 9 14 14 9 10 11 19 4 15 10 16 3 14 4 1 9 f 2 2 2 14 7 5 6 13 14 14 16 12 13 13 9 2 9 12 16 11 20 1 12 5 12 20 g 16 8 7 5 1 18 12 8 1 13 13 8 13 2 17 10 12 1 9 11 10 13 5 18 17 12 h 17 13 6 13 17 16 14 1 10 5 6 19 20 1 6 16 16 10 6 12 3 13 15 19 16 6 i 15 12 20 3 6 12 9 17 4 7 1 9 19 9 11 7 5 5 7 9 12 6 5 1 1 10 j 14 12 19 11 1 12 14 12 14 10 12 8 18 4 9 4 13 4 10 13 1 1 2 14 19 14 k 19 1 7 17 5 4 15 9 14 5 7 3 2 12 14 20 14 15 8 12 10 8 5 19 16 3 l 4 15 7 7 1 4 6 6 15 15 15 15 6 15 3 17 9 6 10 15 18 13 20 16 19 20 m 14 19 13 14 14 5 12 5 11 5 16 7 18 10 14 16 16 19 7 4 7 16 15 2 15 9 n 11 6 17 15 5 2 17 13 17 8 8 10 16 2 13 6 3 9 13 4 11 19 6 17 18 7 o 20 13 6 3 1 20 4 7 2 12 19 9 19 2 4 2 16 4 1 10 18 15 15 14 7 2 p 19 19 20 3 4 6 14 18 11 1 19 3 9 7 10 14 13 14 12 17 7 4 3 2 6 15 q 12 20 7 15 17 20 20 2 12 20 13 11 19 14 16 12 9 17 7 4 8 10 19 5 13 4 r 8 2 9 14 13 2 18 19 20 18 19 10 14 11 5 7 20 14 5 1 12 11 9 19 2 9 s 17 1 10 4 5 18 5 13 16 15 2 17 9 18 14 12 18 9 4 8 11 9 3 6 17 16 t 3 5 7 7 3 13 5 14 19 3 16 15 16 9 16 1 1 17 18 8 11 17 18 16 4 18 u 12 5 6 17 20 16 15 6 19 5 8 5 9 14 8 7 10 2 5 14 12 16 15 8 14 5 v 17 16 19 4 12 10 2 16 5 13 12 17 2 7 16 15 8 11 18 10 17 4 2 7 11 4 w 5 11 8 20 7 13 18 17 20 20 20 11 5 13 12 4 5 13 12 10 11 17 1 11 13 12 x 3 10 12 10 10 2 9 13 13 3 1 12 2 14 1 14 15 12 6 19 7 18 14 6 13 12 y 13 6 13 8 15 19 9 17 13 7 12 3 18 10 20 6 4 14 14 12 4 8 16 4 16 12 z 16 18 11 12 6 7 2 15 8 5 20 13 4 16 10 9 18 9 7 17 11 5 19 13 19 19 Difference between maximum and minimum odds: 0.004783609999999994 [1] https://en.wikipedia.org/wiki/Letter_frequency#Relative_frequencies_of_the_first_letters_of_a_word_in_the_English_language [2]: https://gist.github.com/arnists/d23194c4c48880979ed0993bd3ec4b7c