Hmm, does a tuna/chicken/whatever small tin hold enough or about the same of seed starting mix a 5 oz. paper cup holds? I don't have such a can or I would measure it myself. That has to be enough mix to feed the sprouting seeds until they are big enough to remove from the cup/tin.
Maybe I should ask this question in regard to this:
At what point do you take seedlings out of a 5 oz. paper cup? I may be screwing that up and leaving them in too long or not long enough.
I use empty yogurt containers, the small individual ones are great for individual pepper/tomato/eggplant seedlings. Just make sure you get the ones that are smaller at the bottom than the top (I think yoplait ones are the reverse) so the seedling is easier to remove when you transplant.
I’ve use the bigger yogurt/sour cream/ricotta containers for larger seedlings.
I also save the large styrofoam drink cups from drive thrus. Hubby and I get our family to stash those in a box in the pantry and we collect them when we visit. Those don’t usually survive the planting season but they were free and they were going to be thrown away anyways. Ditto the large el cheapo plastic cups from the drive thru. Those sometimes survive several planting seasons.
Even if you don’t use any of these things you might have relatives/friends/coworkers who do and might be persuaded to wash them out and keep them for you in return for produce from the garden. Or for decent seedlings for their own vegetable patches.
I’m not an eco wacko but I am el cheapo.
My tuna cans are all 5 oz. I use them mainly to pour beer in and sink them into the dirt to catch/kill snails and slugs.
I usually don’t take stuff out of the containers per se. I just cut through one side and kinda tear off the bottom, and plop the plant into the ground at transplant time.