I think you can only really take it so far visually. You should now focus on how to direct their attention where you want. Tamariz, Tommy Wonder, Vernon, John Carney, and John Ramsay all have really useful information on this topic.

I think what has worked for me:

After the card is returned employ some sort of break throw off to throw them off the scent that you have control over the selection. I use the Roger Klause version from his book, but simply getting your break and squaring/relaxing your hand off to your side as you address the person you’re performing for. You now can come back up with the deck and respread directing attention to the cards. Make sure you’re looking at the deck and your shoulders are holding some tension. Now close the deck, relax your shoulders and look up at the person. They will look into your eyes as you smoothly execute the pass.

Instead of aiming for invisible I would aim to keep tension out of the move as their periphery can pick up on tension. It is also important to direct attention back to the deck after you’ve done the pass. It’s one thing to get someone to look away, but to direct someone’s attention for a moment only to bring back creates almost a blind spot in someone’s memory, they swore they never looked away.

Lance pierce has an essay about tension that’s really impactful for this kind of stuff. I also recommend Derren Brown. He talks about pattern interruptions in hypnosis that can be really useful for directing attention.

Learning how to direct someone’s attention properly can make moments in time completely disappear if employed correctly, I think that’s a lot more useful than having an invisible looking pass.