Because I re-invent the wheel, here's another cube. Before you slice, make sure the axis labels match your machine.

The lettering doesn't look great. Not sure if that's from my design, or because of my printer calibration.

2023-04-28:

Added an L shape that's more interesting. It has 0.250" cross-holes. I used this to investigate horizontal expansion to get my hole sizes close to design values.