Hello fellow Simmers!

I am absolutly new to modding and I have the following idea/goal and would love your help, tips and tricks!

I am using Master Controller to change my Sims pregancy clothing and it is a real hassel to try and find clothing that works with a baby bump ingame. So I wanted to add a little pregnancy icon to the thumbnail of the clothing, so I can actually just see and find it no problem. I wanna use the pregnancy icon from the game and already have it as a PNG and I have found this tutorial of how to change the thumbnail of CC Clothing or clothing in general. I am now wondering if I have to use the S3OC to clone the game clothing and then change the thumbnail or if there is an easier version, or basically how I can find the games clothing. Maybe there even is a mod for this I haven't found.

I would appreciate any help, link to tutorials or even an easier way to find pregnancy compatible clothing in game!

Thank you very much!

Superminion

EDIT:

I have played around a bit but I just CAN'T get my custom thumbnail to show up ingame.
I opened the CASTThumbnails.package with S3PE, found the default wedding dress, copied the png to file, saved my thumbnail over it, saved it without renaming, then imported the png and saved it. When I try to start the game it says I have an invalid lizence, the CASTThumbnails.package reverts to the original and my changes are gone. So I am obviously doing something wrong, I guess trying to change the thumbnail like this is not going to work.
When I tried replacing the thumbnail with S3OC or making a clone, changing the thumbnail there and then putting the package in my game, it showed the dress as custom clothing, but the thumbnail still wasn't showing as I wanted. There has to be something quite obvious I am missing, but I really can't figure out what it is.

This is the style I wanted to use:

Short answer, you can use S3OC + the Include Thumbnails option OR delete the thumbnail cache in The Sims 3 > Thumbnails, launch the game and look at the items you want thumbnails for, and they'll be generated back into that folder when you're done.

Long answer is just a couple of notes,
1. Because Sims in their maternity outfits already hide all incompatible clothes in their CAS, I suppose I'm not seeing the utility of this to begin with? Unless you have CC that is showing up that removes the baby bump, which would be an issue with the CC being flagged for maternity incorrectly and it's this that should be fixed.
Alternatively, if you're trying to avoid a Sims outfits ever being changed by reaching maternity-

2. You can use EA maternity default replacers. OneEuroMutt is known for having added maternity morphs to just about every piece of clothing. Buckley has some more polished ones available, too.

Thank you for your answer!

I thought it would filter out incompatible clothing, but when I went inside CAS and chose some Island Living clothing it wouldn't show the baby bump, so I assumed it didn't?
Well... then I guess I've spend the last 3hours for nothing, I guess :D

An addition, as I replied in the same moment you edited the post:

CASThumbnails is just a cache file and not something to overwrite. Replacer thumbnails need to be exported from there, imported into a new package, swapped with right click 'Replace', and installed like a regular mod. Then the cache should be deleted, for the game to reload it.

Unless it's an EA item that is misflagged, maybe your MC CAS settings are clearing the filters that usually apply when a sim is in maternity wear? As by default, only a small pool of clothes that are compatible should be showing.

Ah, that makes sense.

Yeah, I think I'll look into my settings for MC CAS. I guess something went awry there. Thanks so much for your reply and the help! I learned a lot from this