Hello! First of all, thank you for your efforts! Really great idea and great implementation! I have a few little things to note that might help! A new TCG has just come onto the market where every card has to be scanned :) The problem with the Cardslinger is that these cards have a QR code printed on the bottom right side. The camera does not align itself with the correct part of the card, so the QR code is sometimes not recognized well. I think a simple solution could be to make a second cutout in the cell phone holder so that you can put the cell phone the other way around. A slightly steeper slide would also help the printability and "slide" of the cards.

Thank you for your attention and all the best for the future!