This milk holder is designed for the hospital milk containers and the 34mm OD reusable milk containers in Medela pumping kits. This design has an interchangeable base for a flat surface or to the accessory mount on the commercial grade Medela pumps. Please pay attention to the print orientation, its designed to be printed to eliminate supports and create strong parts. This also requires no additional hardware because of the use of locking clips.
I've included the fusion 360 file if your situation requires modifications for different bottles or accessory clips. As I was in a hurry to produce this part for my wife to avoid spilling milk, I didn't make the models in the best way and so the feature history is messy. I violated the principle rule of having an idea before you start to model.
If you are needing a holder for a large bottle, please see my other design.