Here's what I saw that was new-to-me...
While the concept is functionable, I just use one of these to whisk away any powder fall-out...
Here's a closer look at the box...
And the back side...
I didn't purchase these since I don't have any problems using the fan brush. I have read, also, that you can put some powder, such as translucent setting powder, heavily under the lower lashes. After you are finished applying your eye makeup, you can use a brush to whisk it all away and the powder will have created a surface to catch the fall-out. I have tried that a couple of times but, it was just easier to use the fan brush alone.
What's your secret for removing shadow fall-out?