CUTE!!! I even found a lady the other day on etsy that takes used pre-folds and turns them into trainer panties too. I have about 7 or 8 pre-folds and shes priced decent to do it too. You just mail her the prefolds, and she does all the work. I bet I could do it but I just dont have the time to do crafts or sewing right now.
ETA: Here is her site
Convert your Prefolds to One Size Fits All by MamaBearBabyWear I think I'll do that with the ones I do have. I never liked the prefolds with covers anyways.