Let's face it water bottles are more stable laying on their sides but can't be stacked unless you restrain them. This model is a simple bottle stacker to neatly stack your water bottles and keep them from rolling around in your fridge.   Can be used anywhere you store water bottles laying on their sides.  This simple model is the solution to problem. You can also use some double sided tape to keep the stacker in place. I used PETG but just about any filament should work.