I wanted a holder for at least 12 USB drives with a few SD and MicroSD slots and it should be in a tall/vertical tower design.

This holder has a small cavity for a 10g balancing weight (those lead weights with a self adhesive side for balancing car wheels). 

The cavity is 21x24x4.8mm in size and you can simply add a pause in the slicer, when the bridging of the cavity starts (layer 28, when using 0.2mm layer height). 

When the print pauses, you can simply put in the lead weight and then resume the print.

To be honest, I think the tower will work fine without the additional lead balancing weight.

I added a version without the cavity to the files.

Printed without support in ~1h50min on my Creality K1 (esun PLA+, 0.2mm layer height).

update (November 2025):
After switching from Fusion to FreeCAD I tried to re-model the USB tower as an exercise in FreeCAD and came up with a slightly different version. It's slightly less tall (5 instead of 6 USB slots) and instead of 4 sides with USB slots, I change on side to 4xSD + 4x MicroSD slots.