This is a very simple parameterized support base for a cylindrical bottle. The use case is for when kids are blowing bubbles directly from a tall bottle, this helps support the bottle and prevents it from tipping over, causing a mess and loss of bubble solution.
The concept and design are very simple, and it can be cutomized using OpenSCAD (requires BOSL2 library import). The parameters let you set the diameter of the bottle, widest diameter at the base, and the height of the support. Every company uses their own bottle size, so please meaure (in mm) and find what works for you. I recommend you give a few extra mm (maybe 2-5mm) to account for mismeasurement, but it works better if its tighter. There is an option in the parameters to add a drainage hole at the bottom of the base which some people may want, but the uploaded model I actually printed did not use the drainage hole.
The main model uploaded is set with a diameter of 78mm and is for a 32oz bottle of bubbles purchased at a dollar store.