You learn how to get the stripes and then make your own design, with poohcarrot colouring ... which nobody buys and you go broke.
(The tube is filled with the carrier material, the actual toothpaste, which is usually white, to a certain level. Above that level, the tube is filled with the 'stripe' stuff, which is usually red, blue or green. Both materials are viscous enough so that they don't mix. Now the trick is to let these two substances out separate ways but at the same time. The toothpaste nozzle is not just a hole at the top of the tube. Instead, it is a longish pipe that reaches down the tube just ending at the filling level of the carrier material. The pipe has small holes in it further up closer to the nozzle. Pressing the tube will cause the carrier material to enter the outlet pipe and press the stripe stuff. The stripe material will enter the outlet pipe through the small holes, which is where the stripes are generated).
I wish I hadn't eaten so much, yesterday!
Going to my school was an education in itself. Which is not to be confused with actually getting an education (Schultz)