I do not think the crates rely on being full to prevent collapse.
I have collapsible crates but they are not high enough for 500ml bottles so not stackable in that sense.
I have large 90 litre crates I got in homestore and more. They are stackable, have wheels and a lockable lid. I use them for bottles and for storing my large sack of grain.
Oh and they are also solid, as in water (beer) proof so if you suffer an exploding bottle or leak, no mess on the floor <!-- s:D --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="

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