Most homemade toothpaste recipes require ingredients like baking soda (acts as a mild abrasive), hydrogen peroxide (3%) topical solution (kills germs), fine sea salt (antibacterial and teeth whitening properties), coconut oil, xylitol (prevents tooth decay), stevia, essential oils, and so on.
Besides, you can also add dried herbs, orange rind, lemon rind, pure vitamin C powder, etc. All these ingredients are easily available and safe to use.
Some recipes also use glycerin, but it is better to avoid using including it as glycerin tends to coat your teeth and prevents remineralization, which in turn, tends to weaken your teeth gradually.
Check out the following video showing how to make a bentonite clay toothpaste.