Caz, i think i know what you might be talking about as i had a few of those for bilby.

They were called contours i think (this was a few years ago).

Halfway between a prefold and a fitted nappy really.

Not a fitted, cos no elastic in the legs and tummy.
Not a prefold cos curved on the leg side.
With a cover over them.

Even back then, rarely saw them for sale.

When you google btw, try googling "modern cloth diapers DIY" "modern cloth diapers sewing" etc, cos many online links i found were US in origin, same thing, just "diaper" instead of the word "nappy". I remember seeing youtube videos too. HEAPS to trawl through. THese were for making your own fitteds, pocket and all in one nappies - maybe prefolds too. Can't remember seeing a pattern for contours, but still worth looking -

in my early research, i had to get my head around
- the different FABRICS used in making MCNs
- the names and functions of the different nappy styles
BEFORE i could go looking at lots of these websites. You need to understand some of the MCN jargon, before these sites will make sense to you (IMO).

hth