Stackable Bottle Holder / Collector

Please take also a look to my new design: https://www.thingiverse.com/thing:2618022

This is a stackable bottle holder for one-way returnable bottles, used in Germany, to carry them back to the supermarket. With the displayed 4 levels, you can carry 36 bottles, but there are also more levels possible.
I don't know, how this is handled in other countries, but in Germany the one-way bottles have € 0.25 deposit. So you have to collect them, and bring them back to the supermarket. I made already a "bottle butler" out of Aluminium sheet, but I wanted to design a printable one. Here it is.

You need a threaded rod M3, about 400-500 mm long, to hold all parts together (with 2 nuts and 2 washers) . In that way there is no pulling force on the printed parts, and so no problem with layer adhesion.
For the displayed 4 levels, you have to print 4x main, 3x tube, 1x feet and 1x handle.
Instead of printing the tube, you can also buy a tube out of plastic (HT-Rohr DN40).
I have designed this