This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/2Fm8EroNbsT

This is more of a printing trick than a great design!

If you want an open box and for example... 3mm walls. It's very simple to create a solid cube in Tinkercad the size you want and export that. Should take you .5s to do that....

Now in Cura, Select 0 infill, 3mm wall thickness and 3 mm bottom thickness then have the print stop, or manually stop the print at the height you want.

The result is an open box with very little effort... :)