This is a smaller version of https://www.printables.com/model/282431-snack-box-for-velomobiles-size-l
Flat rectangles are for (self adhesive) velcro, so the box stays where you want it.
Printed in PETG, 0.3 mm, 2 perimeters, some support for the lower sections.
As always: 3mf files looks odd in printables' 3D viewer because of modifiers.
The author marked this model as their own original creation.