Summary

An universal and highly configurable bottle cage for your bikes.

Though it was primarily created to hold standard, mini PET bottles,
it can be tuned to fit any other type of bottle too.

Some features:

only one part to print
completely configurable
bottles can be put in upright or upside-down
mounting bracket supports flat or round surfaces
optional cutout for front derailleur clamps
mount it with screws or
mount it with zip-ties (linear or radial)
more than 30 variables to play with

Instructions

MEASURES

The default values in the OpenSCAD source file perfectly fit several 0.5l, 64mm diameter PET mini bottles.
I am not sure about international standards, but at least almost all our German 0.5l bottles ("Mehrweg-" and "Einwegpfandflaschen") will fit.
You only need to modify/tune the mounting options (frame diameter, screw parameters, etc...).

bottle

diameter, mid
diameter, top (for upside-down usage)
length (usually 1/2 up to 2/3 of the bottle)

bike

frame diameter
screw distance
screw diameter
screw head or washer diameter
frame nut diameter
frame nut height

Keep an eye on the screw position (height) and bottle size and make sure the bottle cage will fit.

OpenSCAD

It is highly recommended to set the variable SHOWCUTOUTS to "1" and disable PUTINPRINTPOS (set to "0"). This will turn on some "debug" (cutout) objects and show the bottle cage in its normal position:

SHOWCUTOUTS =   1; // show cutouts: 0/1 (off/on)  PUTINPRINTPOS = 0; // enable preferred printing pos.

It would not make sense to describe all the OpenSCAD parameters, here.
The source file contains a description for each of the variables and most of them should be self-explanatory.

If something is unclear, modify a value and observe the changes in the 3D view.

For STL export, set:

SHOWCUTOUTS =   0; // show cutouts: 0/1 (off/on)  PUTINPRINTPOS = 1; // enable preferred printing pos.

PRINTING

If these two variables are equal, this thing can be printed without any support:

clampExtTop = 0.0;  // length extension (top)  frameExtTop = 0.0;  // length extension of frame mount (top)

I printed all by bottle mounts with an infill value of 30%.

MOUNTING

a bit of rubber tape (insulating/elecrician's tape) is highly recommended, especially for the zip-tie version.
...

Bike Bottle Mount