What could this be? A container for letters or envelopes? Or maybe just a conversation piece. I just thought the geometry was interesting. Here is a 20 second 3D video of the part:

https://youtu.be/eSAMSBqJOb0

The STL file is slightly different from the photo and the part I printed - I tweaked the geometry a little to make it a little easier and quicker to print. The version I printed took about 17 1/2 hours @ 0.200 mm layer height.