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 that I use to refill a small 300ml shampoo bottle kept in the shower using a less expensive but bulkier 1L refill bottle. However, you can use the customizer to select the thread sizes suitable for any plastic bottle size you need. Simply measure the diameter across the threads of your bottles.