It is Stackable! There is also a non-stackable, flat-bottomed version. There are 2 versions of each. One says “milk crate” the other is plain. Put your own name on it. I used Techniqu font in Tinkercad.
The stackable crate (S) needs support for the bottom edges. I had to use a support blocker above 2.0mm, otherwise mine would print it in NON-VASE MODE even after passing 2.5mm layer height. The flat-bottomed crate (F) does not need support.
