One of the coolest card gaffs is the Modern Flap Cards by Hondo. He makes the as a premade gaff, or as a video where you can learn to make your own. The video is the way to go, as you’ll be a lot more versatile with what you can do. There’s a little bit of a learning curve to making them, but it’s really not that hard.
I use one in my preshow video in my cruise ship show, and in a lot of social media videos. I haven’t used them in a live show, simply because I don’t really have a place for them. The problem is a playing card is small, and the change is hard to view from the back row.
It hit me a while ago that you can do the change with the card isolated in a cup. I hadn’t had time to really play with it before the self quarantine, however I played around with it and here’s the card color change change in a cup:
There’s a little bit of knack to do the move in a cup. In a nutshell I’m using the weight of the card to keep the change from happening. It’s all about the angle you lean the card at. I think the next time I make some of the flap cards, I’m going to have a bit less tension, so that I have more wiggle room with the angle of the lean.
The discovery of doing the change in a cup is the direct result of playing with the gimmick and a good example of why you should be playing with gimmicks beyond what’s in the instructions.