Rembrant makes 3 ounce containers of toothpaste.

Shave cream and gels are easily available in 2 and 3 ounce cans, or you can get a bar of shaving soap that will last forever and not have to worry about (also in travel size)

Toothpaste is sold by weight, not by volume, so that adds to the confusion (though the TSA considers an ounce to be an ounce either weight or volume).