I remember when Stripe toothpaste came out in the 60's. I thought it was pretty cool. Ever since then I have wondered how they get the stripes in it. I don't know why it took over 50 years for me to do this. There was a empty toothpaste tube sitting in the bathroom, so I decided to cut it open to see what tricks they use to get the stripes. As you can see in the photo, there is nothing mechanical on the inside, just and empty tube. That was disappointing because I was expecting some channels or chambers to be in there. If you read the Wikipedia article it only mentions pipes and nozzles for getting the stripes in there. So I went to YouTube and found this video. You can find other videos. It all comes down to this simple method which is easy to manufacture.