It´s a little box to make unused space accessible.
espacially for Pinhole Patterns of Ikea-Method kitchen funiture.
Note:
I increased the Vertical shell Perimeters to 5, to avoid infill in the Walls.
To make everything look smooth, I recommend these Pinhole Plugs
(https://www.printables.com/model/161284-ikea-furniture-pinhole-plug)
to cover the remaining Pinholes.
The author hasn't provided the model origin yet.