Shampoo bottle transfer adapter - customizable

Connect two bottles to transfer shampoo, soap, conditioner, or other thick fluid from one bottle into another.

I've included an STL file for a 28mm-24mm adapter which I use to refill a small 300ml shampoo bottle I keep in the shower from the less expensive but bulky 1L refill bottle. But you can use the customizer to select the thread sizes for whatever sizes of plastic bottles you need. Just measure the diameter across the threads of your bottles.