This is a stand for Adafruit's Tiny Thermal Receipt Printer (aka DP-EH400). It provides a tidy way to route data and power cables out from underneath the printer. It features a socket for this 2.1 mm power jack adapter and a slot for a right angle mini USB cord.
The stand is not a complete enclosure. The printer sits snugly in the socket and can be pinned in place with screws through the provided side holes, but I don't recommend mounting it any orientation other than upright.
Slic3r settings: 0.3 mm layers, 3 perimeters/top/bottom, 10% infill, no supports.
Some sanding may be required to clean up screw and cord holes.