I wanna try and cross-pollinate tomatoes to create my own hybrids to suite each years weather or just experiment. I want to be sure of what varieties they are but on a self pollinated plant that is reallllly hard.
I would try *carefully* removing the tissue that encloses the reproductive organs (maybe with tweezers and/or and exacto knife) and then removing stamen (male bits), or atleast the anther (tip) from the flower you want to pollinate with a different plant right after the flower opens, maybe with nail clippers or something similar. Then remove the flower of the plant you want to pollinate with or use a Q-tip or painbrush (I prefer a paint brush) to get pollen from that flower and brush it gently and in great quantity onto the pistil (female bit), specifically the stigma (the tip) of the flower you want to pollinate... Never actually tried it... but it works in my head...
If you snip off the anthers, it will greatly reduce the risk of self-pollenation. If they are left on, then they will develope and quite possibly some of the pollen will end up in the seeds (each seed is like a baby, requiring its own bit of pollen to make it), and you would not be able to tell which is which.