I love this - Instead of doing polaroids (which don't always turn out that well and the photo paper is costly) have people take pictures on their phones and print out a copy to leave with the host/wedding party/etc
It’s called Elasty and it was created by designer Yoori Koo. It’s a silicone bumper fitted with elastic strips which allow you to stash your headphones, pens, cards etc. on the back of the phone. smart!