Tomatoes are slightly more complicated. I save the seed, juice, and some pulp in a plastic cup, add some water, cover with plastic with some air holes, let ferment for a few days (outside, out of direct sun), stirring daily, until the seeds separate from the pulp. Rinse, dry on a coffee filter or paper towel. Save in a pill bottle, test tube, or similar container. Label!
Only use “heirloom”, or other “open pollinated” varieties.
Thanks for the tips!