This is a 3D-Printed bottle holder for your bicycle.
It is not special in any way, but it simply works, looks good and is also rather easy to print.
It should be printed from PETG or a stronger material, PLA will flex too much if it gets heated up in the sun. (White PLA might work since it does not heat up that much).
You can use the standard print settings from your slicer but you will need supports.

The standard inner diameter is 70mm, therefore it will work best for bottles with a diameter of around 75-80mm but you can easily scale the model in your Slicer.

Have fun!