I tried a bunch of toothpaste solutions on here but none really printed cleanly enough or worked simply enough for me. I made my own and its the best I've tried so far.
Printable in upright orientation. May be scaled in inches, if it looks small in your slicer, scale up by 2540%.
I printed at .2mm layer and it works well.
Fit of tube is perfect for my printer's tolerance. If it is too tight, scale up X&Y. If your toothpaste tube is too wide for this, scale up Z.