Link to zip file containing final Sims 3 export package, clean Sims 4 package, Texture file, original texture files, .blend files from each step of the process. TSR .wrk file(Uploaded to google drive because file uploader says error 500):
https://drive.google.com/file/d/1Eh...iew?usp=sharing

Ok! So here is my issue. The tube loses all transparency in game, turns red, and honestly kind of looks like hot garbage. Which I'm sure some of the texture quality is lower graphic settings (medium) nothing else looks THIS bad.

I am converting this fabulous science tube to Sims 3 from Sims 4.
I exported the Mesh via Sims 4 studio.
I opened in Blender and moved the UV map pieces for each mesh object so they'd fit together nicely and could be merged into a singular object to match the group count of the flamingo lawn item.
After completion I compiled the merged texture in Gimp, exported as single layer png.
I imported the image into blender and made sure the UV map lined up with the texture. Saved, opened in a different version of gimp and exported as ,obj with the groups option ticked.
Imported mesh back into tsr, looked fine enough.
edited and clicked "made empty" un unwanted image files.
Saved and exported.
Now I'm here!

I do not know what caused the tube to suddenly turn opaque, or why it's now so doomy looking once it's in game. If anyone has any ideas I'd greatly appreciate any help!

The texture issues have been caused by accepting the prompt about mask width for the 'Make Empty'.
Make Empty can also cause some issues itself- I'd recommend importing blank textures manually (tiny 32x32 red square for Mask, tiny 32x32 black square for Specular).
Only select yes to the prompt for mask width on the Overlay, no for the tiny textures.
The Multiplier shouldn't be blank, that's what's making it turn red. Usually the overlay is reused for it, on this type of conversion.

Partial transparency, though, is a little unreliable. I couldn't find any objects that aren't all-or-nothing / using transparency to cut out parts entirely. You can make a version of the overlay with the glass parts removed / black on the alpha channel and use that as the Multiplier, then experiment with the Alpha Mask Threshold (Mesh tab, click material then the ... button that appears. Alpha Mask 0 is opaque and 250 is transparent- maybe a value between the two will have the look you want, but I suspect it's not controlling opacity but rather what shades of grey to cut out.).
I didn't have much luck looking into that, maybe someone else will know the trick to it!

I can only suggest maybe separating the glass parts and using sculptureBathroomHutch as your base so you can have 'real' glass with the glass shader instead, which will work for certain.

Best of luck

It appears all opaque in game because your mesh only has a single group. Even if you tinker with the alpha mask threshold values it will affect all of your mesh. You need the glass tube part in a separate group so that when you change the material definition values it will only affect that group only.

And yeah agreeing with everything @CardinalSims said above, never make your textures empty including the specular. If you don't need your object being CAStable, just make your multiplier gray, the specular black and the mask red.

Also some related tutorials:
https://murfeelee.tumblr.com/post/154960947076/sdkfj
https://deniisu-sims.tumblr.com/pos...ate-the-correct
https://web.archive.org/web/2022060...able-glass.html
https://web.archive.org/web/2022060...hong-alpha.html

Thank you very much! I'll give that a try!

Thank you so much! I'll check out these links right away!

To what @CardinalSims said about alpha transparency masks... In Gimp, I use the 0 (black fully transparent) to 100% (solid) scales, and you can get a good transparency at between 85 and 98%. I generally use hair shader for garments. Cmar's tutorial uses CasHairSimple, or something like that. A certain degree of transparency, or semi-transparency can be done with phong shader. I actually used it to make doll hair once. But yes, I also think glass shader would work best for OP's object project.

This helped me connect the dots on what I saw while experimenting.
Alpha Mask Threshold goes 0 to 255 because it represents white level on the alpha, not opacity. I did get it to work on a single group without phong alpha, but only for cutting out parts of the texture entirely (invisible transparency).
A shortcut of Deniisu's method would be to eyedropper the darkest shade of grey on the alpha instead, then simply look at the the RGB value. No need for calculating- the colour picker already shows 41% grey to be 104 RGB.

I'm guessing phong alpha is required for partial transparency, or adjusting the Transparency value itself (0. to 1 range) for the entire group for phong.

It's confusing when coming from a background in CAS creation, because SimHair shader etc labels it the other way around (the Transparency value 0. to 1 is the white level tolerance, not the opacity). Bizarre