Thanks Mama sells individual flats, along with the relatively hard to find Imse Vimse muslin flats.
If you buy a dozen flats from Mom's Milk Boutique and use coupon code COVER12 you get a free one size cover, for a limited time! I can't wait to see what I get.
I have some small hemp flats I can use as doublers, and will probably make myself a flat or two from bamboo... don't know yet. I may make myself a new diaper cover, too, if the urge strikes when I've got time.
The rules are (and this is not a complete list of rules, you can find those HERE) that you must use flats only, and you're only allowed to use (up to) 5 covers. Nighttime, you should try to make flats work, but if you can't, it's ok. You can use flushable liners but not a diaper sprayer.
When the challenge is over, feel free to come shop for some pocket diapers at my Hyena Cart store! They can be stuffed with the flats you just got done using, or the inserts that come with them. If you would rather get just the pocket shell and use your own insert or flat, email me and I will get you a custom listing up.