I sewed a basic fitted nappy from a towel, loosely based on an old cotton terry tots bots size 3. Terrible mobile pictures, sorry.
https://i1345.photobucket.com/albums/p666/teddynorman/IMG_20141113_101842_zpslomshg6u.jpg
https://i1345.photobucket.com/albums/p666/teddynorman/IMG_20141113_110739_zpscarnvplb.jpg
https://i1345.photobucket.com/albums/p666/teddynorman/IMG_20141113_110745_zpsptzwfw2t.jpg
I didn't allow enough seam for turning the nappy the right way out on the wings, so had to chop them off and make some new ones.
I'm crazy about the snappi, I even unpicked the velcro from some other fitteds I have. Sophie was always telling me that it was scratching her.