So far when I have been creating items containing glass or a plant, I have cloned from a similar item that already contains these properties.
My problem is what to do when there is no similar item that I can use to clone from?

At the moment, I am creating a bookshelf that not only has books ( ) but a few decorative sculptures including a plant perched on the shelves.
I cloned from the First Class Shelves (Glamour Life) which has a few accessories; however the surrounding area around the leaves of the plant are not displaying correctly.
I am also working on a Double-sided Cabinet which has glass (that I had to add in the GMDC) but mainly displays transparent. I am really limited with items to clone from for this.

I have browsed several tutorials and these forums looking for any suggestions or solutions but unable to find out what I can do.
Thank you in advance for any assistance.

Update: added pics

These two tutorials should cover everything you need: Be sure to read the comments section as well as the tutes themselves.

https://modthesims.info/showthread.php?t=71559

https://modthesims.info/showthread.php?t=220244

ETA: Oh, a thought on the plant: If you are including it in same subset with other decorations on the shelves, whatever transparency settings you have in the TXMT probably won't work for both the regular objects and the plant. It should be its own subset with its own TXMT to get the transparency right. OR, just make a container slot on the shelf and create the plant as a separate object that can be placed in the slot.

I remember seeing this post by Pixelhate a few years back, it contains a lot of information about Sims 2 Material definitions, including things like glass effect, reflections and transparency.
https://modthesims.info/t/316260

Glass is really no different to add than a regular subset. It's probably the settings you're having troubles with. If you add a regular non-glass subset, half the job is already done, and all you have to do is to find a glass material you like.

There's a few ways to add glass
- A glass TXMT without a texture (a "cheaty" way - find an object that has one, use the "Export" button in the TXMT, then make a new subset and all that for your object, and import these settings. You get all the settings from the TXMT. Make sure you check that all the tabs have the right names, and if there's any shaders mentioned you have to add them to the file list.)

- A glass TXMT with a texture (you can use the same trick as above, BUT make sure the "stdMatBaseTextureName" line and others are correct according to your object, because they'll be copied down according to the object you extracted from, and you don't want that).

For the mesh, make sure to use the Opacity line in the Comments (if you use Milkshape) correctly. Glass and transparent objects need to be layered properly to show properly, and if you export as OBJ it imports according to name, not layers. If this gives you trouble, export as Unimesh. Then you get them as layers (but make sure you keep the subset names and don't change the GMDC filename)

For the texture, use DXT5. It's best for transparency. DXT3 can work if it's an even texture. Don't use import or DXT1.

Main settings for transparency (greytones) should be
- stdMatAlphaBlendMode: Blend
- stdMatAlphaTestEnabled: 0
Transparent parts should be in one or more separate layered groups, otherwise you can get some weird results.
Other than that it's up to you.

Plants and other non-transparent (black/white) alpha'd objects should be
- stdMatAlphaBlendMode: None
- stdMatAlphaTestEnabled: 1
Can be in the same group as the rest of the mesh, except for transparent parts.

(If there aren't any alpha or transparent parts and everything is fully opaque, settings should be "none" and "0")

(If you have parts with textures that are a blend between transparency and non-transparent alpha, put these mesh parts on "Blend" and "0", but be wary of how you layer the mesh, as "Blend" can behave very strange with opaque textures if you layer the mesh wrong)

For non-texture transparency (single-colored items like glass in windows, doors, etc.) you want to add the color in the settings. I'm no expert here, but the tutorial above shows how. You can also copy color settings from items you like.

(Edited to add a few things)

Hello @d4RE
Thank you for this,
I especially like the idea about creating a slot and placing a plant as an alternative.

Hello @SmugTomato
Thank you for this link regarding glass and transparencies.

Hello @simmer22,
Thank you for this information - I especially like the idea of creating a new subset for the glass and will take on board about the settings that you state.
I will also check out the stdMatAlpha info re the plant and let you know how I get on.
Thanks again - you are always so helpful.

Hello @d4RE, @SmugTomato and @simmer22,
Just to let you know that I have had success with the plant on the bookshelf and also a couple of glass items I had been working on - so thank you all very much!

That's wonderful. Congrats.