This is basically an inverted standard calibration cube, and prints in about the same amount of time. But this one is hollow to test retraction, overhang angles, and an insanely difficult bridge at the top.

The cube measures 20x20x20mm and has 2mm thick walls.

I recommend using 2 perimeters to maintain the gaps in the Z at the top.

Please be aware that the .obj file includes a small loaf of bread, which is not present in the stl file. Thank you for understanding.