We found this small wall shelf on Etsy. It looks like it’s 3D printed and connects to the wall with simple screws. The actual shelf slides out to reveal a cash sized compartment below.
Available in 16 different colors, this inexpensive knick-knack shelf would make a great place to keep shared keys, pass cards or some emergency cash. Guests would never guess that picture of Grandma was sitting on a rainy day fund.