I'm about to make some and might try a couple varieties. On pinterest, I saw one kind that had fleece on one side, with maybe 2-3 layers of flannel. I'm guessing the fleece side was to wick moisture away from the breast, and you'd wear that side in. I also saw just plain flannel, in a few layers. I also saw some using old prefold diapers. I can do any of those, and perhaps I'll try all three.
If you've made and subsequently used any, what material or thickness did you like the most? I am mainly making these to wear at home and at night, am ok doubling up if needed but want a decent stash of at least 12 or more. When out, I usually wear a disposable variety just so I know I won't get any wet shirts.