Updated: May 29, 2020
I used this tutorial as a reference for making the toothpaste.
To create the toothpaste tube, I tried several materials to try and create the cylindrical shape. I didn't want to use a straw and it may be difficult to paint white due to the surface.
I tried to use standard cardboard and curled it around a paintbrush, however the cardboard crinkled far too much to give the illusion that it was a tube. Next I tried to used some tine, again it crinkled too much.
Then I tried using toilet roll cardboard, which is much thinner than the cardboard I previously used. This worked MUCH better. Using hot glue to seal the ends together to create the tube. Next I put some hot glue into one end and used tweezers to pinch the end to mimic the closed end of a toothpaste tube. I didn't need to seal the other end as it wouldn't be visible in the short.
With the tube now complete, I decided to make purposeful creases in the tube, and filled it with silicon (the type you use to seal tiles) to maintain the shape. After 24 hours, allowing the silicon to cure, I painted the tube white to fit with the colour theme.