@LexYeen split the deck into two roughly equal parts. Then turn upper corners towards each other. Lift from the bottom of those corners with your thumbs and use the rest of your hand to keep the decks down and put the cards under tension. Let your thumbs slide up the corners, which should feather the cards together at the corners. Then tamp them into alignment. Repeat procedure 3-7 times for proper random distribution.
@LexYeen @kelseyhusky Hate to say it, but it just might be a thing that doesn't work for you. My mother has never in her life been capable of shuffling a deck of cards. It was a running gag for a while... then just became a silent fact of life. *hugs* I'm amazed I can manage it at all, not that I've even tried lately.
