These connectors allow you to refill travel/trial-size toothpaste tubes, which are much smaller and prefect for travel and camping, from larger home-size tubes. The connectors are sized for the two most popular US brands of toothpaste: Crest and Colgate. 

To use:

1.  Connect the larger tube to the smaller one. Screw until the ends of both tubes are firmly butted together. This will keep the paste from leaking out and eliminate messy cleanup.

2.  Squeeze the larger tube until the smaller one is full. Do not overfill because the pressure will cause the paste to leak out when the tubes are separated.

3.  Expand the larger tube a small amount by squeezing it in the wider dimension. This will relieve pressure in both tubes and retract some paste back into the larger tube.

4.  Unscrew the tubes. 

5.  If done properly there will be no leakage or toothpaste left in the connector

The files include:

1.  Crest to Crest transfer tube (green in the photo)

2.  Colgate to Colgate transfer tube (blue in the photo)

3.  Colgate (top end in the STL file) to Crest (bottom end in the STL file) transfer tube (blue and green in the photo)

These files have been upgraded to the latest design: Starting threads on both ends of the transfer tube.  The original transfer tubes had continuous internal threads, with a starting thread at one end and an ending thread at the other. The ending thread was difficult to thread onto the toothpaste tube. If you look at the threads on toothpaste tubes you will note that they are going to be easy to print in one direction and almost impossible to print in the other. 

Here is what works for me, most of the time. Print with 0.2 mm Quality layer height. Modify the predefined setup for your filament as follows:

1. use a Brim

2. turn Detect bridging perimeters OFF 

3. set seam position to RANDOM

4. MK3S works better than Core One

I clean the threads with a bottle/test tube brush and a sharp 45 degree tweezers.