yeah, but aren't O.B.s like the size of my first pinkie segment?
When I use ob tampons, I have to use the big honkers. Only the wee little ones are so small (and I think I'd say even the smallest size is larger than your first pinkie segment). Regardless, you get used to whatever you use. If you're committed to a healthy body and healthy environment, you're absolutely willing to try new things and disregard what the media tells us by way of commercials.
I also think that knitting on a small enough needle, you could work in the round right down to the I-cord for the string. Otherwise, I can think of a couple of methods to prevent the string from tearing and "stuffing" from being left behind. Personally, I would absolutely trust something I had made myself with TLC before I would trust something manufactured and marketed en masse.
Fortunately, I use a combination of non-stop medication and Insteads for the periods I do have to combat my anemia, but once my situation changes, I'll be back to Diva Cups, homemade liners, and some small handmade tampons like these! Great idea!