OOO you want to create more seeds from the existing plants you have. This can be fun. Done it with a auto x auto backcross onto its sister.
growdiaries.com/diaries/129779-grow-journal-by-m0use
Few things to note.
** reversing a plant requires silver, some forms work better **
1) Auto is resistive gene trait, meaning if you mix auto genetics with photo genetics it will result in "fast" flowering photoperiod plants. not fully photoperiod not truly an autoflower.
2) When making seeds out of Fem genetics, you only want to do it a few times no more. My rule is one and done. When you cross fem plants it's making their genetics a bit retarded, The first set/generation of seeds will be ok. every other set/generation made from the last generation of seeds will be worse and worse, it is not advised to keep making seeds out of seeds from previous projects as their is no true males and its getting messy. Low germination, high hermies and other weird mutations happen.
3) you can not consume the reversed plant "pollen producer/dad" as the silver is not good for your body.
So with that in mind you need to pick a donor "pollen producer/dad" and receiver "pollen whore/mom"
You will want to start the receiver plant earlier by a week or two then start the donor if they have similar growing times. This way the receiver will have lots of sites to receive pollen.
Then you need to pick what silver you will use. The two most available options are Colloidal silver aka CS or Silver Thiosulfate aka STS
Bother have their own ups and downs. Silver has the ability to block one of the female hormones in the plant and then it produces male parts like sacks/balls.
sacks/balls on a fem plant = fem pollen. fem pollen + fem flowers = Fem seeds.
CS
ups: cheep, more available then STS, can make your own with a few tools for cheep. comes in many strengths. Min 30ppm max 500ppm, Long shelf life, does not matter if it human/pet/project grade
Downs: Does not work as well at STS, more applications are needed and hard to tell its strength on home made,
STS
Ups: works better, less applications, a little can go a long way. Long shelf life when the two components are kept separate.
Downs: costs more oz V oz, hard to make at home without a former education on the matter, does not last as long, around 1yr shelf life once fully mixed. Can be made too strong and cause issues. has two components to be mixed if you want longer shelf life, other wise 6-12 months... ish.
If you go the CS route "what I did" many options. get something that's at least 30PPM and has like 200ml, if you go STS route, try and find a production date, you want stuff that's less then a 1yr old.Their is a person on this site who made their own STS using the compounds and mixed it up. they do a good job but its a process. with weaker solution of CS you need to spray it daily with STS you spray it once or twice a week. both options you stop once you see male sacks/balls forming on the donor plant. Once this happens wait for the sacks to open. Can spread the pollen around manually or let the air fans do it in the tent. Once pollinated, the pistils will brown at the tip and slowly brown moving down. The seed will then take about 4 weeks to develop. I run my receiver plants, the ones making the seeds, extra long. Like 6 weeks to ensure they are fully mature and ripe.
Their will be some back crossing of pollen from the donor plant, you can use these seeds as well but they will not be the same as the ones you made with the donor x receiver plant. it will be donor x donor and a selfed back cross. If you want more of the same strain its best to use two plants. eg two Purple Puch Auto or two California Snow Auto and cross one with the other following the system donor x receiver for better results.
Once you have the seeds in hand, let em dry out in a warm location for a week or two after harvest and then bag em up. keep them cool and they should last years. Can toss out any small white looking ones as they are not likely mature. Some plants make very textured/spotted seeds, others make matte brown/beige/greenish ones. Do a germination test of them in a glass of water with 5 seeds and see how long to they take to pop. Not all crosses yield great seeds. if all pop within a few days time call it a success. They should carry over traits from both parents.