here's the instructions I used: https://www.autostraddle.com/make-your-own-tarot-card-pouch-that-doubles-as-a-spread-cloth-356258/
couple of inaccuracies here:
1) elastic should be sewed 8.5" from the edge, not 9.5"! learned that the hard way
2) "It’ll take less than an hour to sew up" lolol maybe if you're already a hand-stitching wizard, but this bears no relation to reality in my experience. I've been working on this for sooo many hours and feel lied to 
my end result doesn't look as tidy and cute as the Autostraddle photos! it's awkward and bulky. maybe because my deck has thick cardstock and 16 extra cards, plus the booklet? maybe it'll get softer and fit better with time. 
I've been super intimidated by this project for ages, which I felt silly about, but now I feel like that was totally justified! but I'm glad I got one done at least while I have this excellent workspace (a clean, wide kitchen bar all to myself) 
@Satsuma thank you! :)