Stackable/expandable USB (and 12V) charging station case

This is a set of elements to build a charging station for both 12V and USB charging. It consists of three basic elements:
* Bottom element (bottom_case.stl) for 5 USB chargers (use this one: https://www.banggood.com/DC-7V-24V-To-DC-5V-3A-USB-Output-Converter-Step-Down-Module-KIS3R33S-p-912110.html) and one 12V socket with a switch (use a standard snap-in switch for cars). A standard glass fuse holder is used.
* Intermediate element (intermediate_case.stl) for 5 USB chargers and one 12V socket, but no switch.
* Top cover (top_cover.stl)
They are screwed together using 6 M3 threaded rods and 12 nuts (one on top and bottom for each rod). On top, the nuts are recessed, on bottom the rods stick out (you need some play for mounting) and you can put the little covers (screw_cover.stl) on top of that for better looks and protection from scratching.

Due to popular demand (the people being me :p) I now added a set of models for a charging station with no 12V socket, only USB chargers. The