You probably want to tweak your box. The included examples are quite small and are therefore not really useful without at least some scaling up. Start with one of the examples in the zip file and look in mybox.scad and cylbox.scad for details on the parameters. These scripts are written from scratch and not based on the ancestor thing, so any existing designs are not directly usable here. Sorry!

To print thin-walled objects make sure the wall thickness is a multiple of perimeter widths, which depend on your printer and slicer. The small diagonal bars are tricky if printing too fast and/or without additional cooling. Printing several boxes at a time is probably a good trick but may cause surface blemishes.