Stackable Drawer System

This is an idea of a stackable drawer system. This is my first try to model something for a 3D printer. I hope that it is some kind of useful.
It is 20cm wide, 15cm deep and so high like you want. All walls are 3mm thick.
To build a full drawer system you need:
1 Bottom Part
at least 1 Middle Part
1 Plate
1 Upper Part
Drawers
The plate is to place under the Upper Part to connect it to a Middle Part