Honestly, if you've never visited Kim, do so! They share an entire series of Homesteading tutorials well worth viewing and taking notes!
Homestead Series How To Save Tomato Seeds
Posted in Down The Garden Path
Growing open pollinated/heirloom plants and saving seeds is great for the pocket book. Not to mention it helps preserve traditional varieties and give your family non GMO produce.
Saving tomato seeds is a little different from other plants, but it's so easy! Simply cut your tomato in half and squeeze out the seeds into a jar. Once your seeds are finished add a few tablespoons of water to the jar. Place a coffee filter over the top and secure with a rubber band. Let this sit in a warm place for 3 to 5 days. It works faster in hot weather. Once done, skim the scum off the top and pour the seeds into a fine mesh strainer. Rinse them well and spread out on a dry coffee filter. Leave them for a day or two, then scrap them off and onto another dry filter. Let them sit for a week or two, to fully dry. Then package into paper envelopes and store in a cool place. If you would like to keep them in jars or plastic baggies make sure they are VERY dry so they don't start to mold.