I'm looking for the mod (tool?) that labels bodyshape clothing and groups them together in CAS.
I scrolled past this on tumblr a couple of times (I don't use bodyshapes in my main save so I never downloaded it) so I know it exists, but I can't for the life of me find it or figure out what to google to find it now that I actually want it.

There's the original BSOK system, plus some variants:

Chris' original BSOK organizer files are kinda everywhere these days, found a few files in this post:
https://modthesims.info/showthread.php?t=649795

And here:
https://gayars.tumblr.com/post/6259...-moving-forward

Here's one with a tutorial:
https://lavenderlight.tumblr.com/po...im-organisation

Pick&mix has a handy editor, too:
https://www.picknmixmods.com/Sims2/...BsokEditor.html

Medieval adaption:
https://plumb-bob-keep.tumblr.com/p...bsok-adaptation
http://www.medievalsims.com/forums/...p?f=101&t=10387

https://blueheavensims.wordpress.co...zation-kit-v3b/
(bluesimsheaven also has some on their adult page, it seems)

Some fantasy kits:
http://www.medievalsims.com/forums/...p?f=101&t=10564

Are you thinking of the BodyShape Organization Kit (BSOK). Blue Heaven Sims has been updating it recently but I believe still has Chris Hatch's original version as well.
https://blueheavensims.wordpress.co...zation-kit-v3b/

That's it! Thanks much