Geomancy on the back of a receipt
Geomancy is the most underrated divination method in the Western tradition, and I will die on that hill. You need a pencil and something to write on. That's it.
Sixteen rows of random dots, count each row odd or even, and four Mothers fall out. From those you generate the Daughters, the Nieces, the Witnesses and the Judge. It's elegant enough to make an engineer weep.
Cast a chart on the back of a coffee receipt Thursday about whether to take on a new student. Judge: Fortuna Major. Right Witness: Puer, which tracks, because he is enthusiastic and impatient. Said yes, with a list of conditions.
Diary entry filed. We'll see in six months whether the dots knew what they were doing.