Apologies. I jumped into this program kind of quickly and have been trying to juggle a lot of different threads, articles, and web pages since. I forgot about you mentioning that article. I'll go bookmark that now and start on it. Thank you again for answering my last questions. I do appreciate it.

I wasn't sure if this would work automatically like most bulbs in a normal socket, or if I had to change something to make it directional?

I couldn't drag and drop the brace. I had to import it with the button in the menu,

I saved the item as a library and imported it into Sweet Home 3D, and it said it worked, but when the brace appeared in my file, it scaled way too large and out of the alignment I thought I'd set for it in the other files. I know I had scaled it much smaller (The same size as the old brace I was using), so I'm not sure what's going on there?

When you said, "You can use a different name for 'light'...

I have the same happening sometimes, I don't know why. Sometimes it helps to just save the library before adding more objects. That is the only reason I sometimes have to use the import button, otherwise I only use drag&drop. Try to drop in the empty area below or beside the columns.

Maybe you mixed up mm and cm? I often create objects 10 or 100 times as big as they should be because the details are too small to edit in Sweet Home 3D. When you import it in the Library editor you can use the x10 or ÷10 to resize the object for usage in Sweet Home 3D without having to resize the actual object itself. You can see the values in the modify dialog when you click one of the buttons. You can also set a default elevation.

In the Library Editor you set the lightSourceMaterialName to the material name as it is in the obj/mtl files. Most existing light models use 'light' for the material name so you enter light as the value for the lightSourceMaterialName.
But sometimes you want multiple parts of the same object to act as a light, parts that have a different material name. You can multiple material names as the value for lightSourceMaterialName. Add multiple material names separated with a space. Be aware that multiple material names from the the same object will use a single power setting to control them all.

So, I did finally manage to find where the Furniture Library Editor was burying the brace in the upper left menu, after sifting through every category, so at least I got that.

So, I'd like to...
1. Get the light PANELS to appear on both sides of the brace so it doesn't look like just an empty space from the left side.
2. Have them both light up.
3. Get the light to shine at a much lower intensity, again, like the reference pic from the show.

1. Is there a way to change the type of light that’s emitting? I saw in the Light library that there’s a ‘Fireglow light source’ and it might be nice to try that.

2. Do you have a coffee account or something I can kick you a couple bucks for all the help you're providing me with? I think I would have given up by now, trying to work through this on my own.

Where your object is in the catalog depends on the preference you have set in the Preferences dialog. Set it to "Searchable List".
In the catalog pane (top left) select the category you have set as the category in the Furniture Library Editor. In the Library Editor also set a few key words that identify your objects. They can be used for searching.
In the catalog search box you can type a (partial) name you have set for your object or (partial) tag names. This search is smart and fast! Even without selecting a category you can find objects very fast by typing multiple (partial) names with a space between them. It filters the list on your search criteria.

Either use a floor with the thickness of the brace which will create a light panel where both sides are flush with the brace or use two panels, one for each side.

With the panels you have you can set a different color to the panel which changes the light. Another trick is to create semi-transparent panels (non-light) with one of the light sources from the catalog between the panels but I don't think that is the right solution for your panels, you won't get a nice even spread light on the panel.

Thank you but there is no need for that, it's all freely offered, just like everything on my Dodecagon.nl site is completely free and open source.

I'm in my file right now but I can't see any way to alter the thickness of a floor. It only has an area to change thickness for the optional baseboard, which I didn't want or need on the light. Under Preferences I see an option to change the new level floor thickness, but but that doesn't seem to be what I want. I'm trying to modify the floor in the initial stage where I first created it. I also tried modifying it after I exported, and then imported it back into the program, but at that point, it's part of the whole object and the brace was already set for 6" thickness. What am I doing wrong here?

Wait, so if I made the color of those panels bright red, I'd get a red light? It makes the color and surface of the panel automatically translucent? When I've been working with the light panels, when I rotate them a certain way, when I get to the opposite side of them, they often disappear or turn invisible, so I assumed that whatever 'color' I assigned them was just replaced by whatever the program uses to represent illumination?

You set the floor thickness on the level. Double click the level tab and you can set the floor thickness. If you don't see a level tab or can't set the floor thickness just add a level and set its elevation to a negative value. Now you can double click the level where your floor is and set the floor thickness. Export/import only your floor object. Now it has a thickness you can adjust to your 6".

You're struggling with several basic concepts of Sweet Home 3D because you are trying to create a piece of furniture with several advanced aspects before you went through the more sedate process of learning Sweet Home 3D. No problem, kudos for what you already have achieved!

Concerning the levels you should read the manual available at the manual page on Dodecagon.nl.

When I made the last import into my project in Sweet Home 3d, it was laying on the floor instead of standing upright, and the light was no longer colored the right color.

Also, I think I jumped the gun on something. I selected the two brace files that were old but there was no way at all to delete them. I tried with the furniture library editor and I thought I had deleted their libraries, but those copies are still in the Sweet Home program and I don't know how to get them out of there. You can probably see them on the far left of a few of the pics I'm sending.

Assuming you already have the brace itself we will recreate the light panels.
Export the room. (With a floor thickness set to 6" it should produce an object 6" thick.)
Edit the obj file to set the material name 'light' like you did before.
Import the object. It should be as thick as the floor thickness: 6". If not you can still change the thickness to 6".
Place the panel in the brace and export both brace and panel together. Import and rotate/tilt/resize/set colors and export the finished brace-with-panel.

I exported the 1 piece light, changed both the obj. and mtl. files, though you only said to do the obj. file, but previously you said that they both have to be changed whenever I change something?

Not many users know this but since the brace only has one material you could simply remove all lines starting with "g " and all lines starting with "usemtl " except the first one of each at the top. Actually, only the "usemtl " line is necessary in this case.

Again, knowledge you would have gained when you had started of a slower instead of diving directly into advanced topics laughing
There's another manual on dodecagon.nl that explains changing material names. Reading that manual will make it more clear what happens when you change material names and the relation between "usemtl" in the obj file and "newmtl" in the mtl file.

Make sure you have the level elevations as mentioned in my previous post.

Check the obj and mtl files and change the material name to "Brace" if you hadn't done that yet.

I named the FILE:'Structural Brace'

In the obj. file for it one of the top lines says,
'mtllib Structural_Brace.mtl'

This is just a tag to find it in the library, isn’t it?
I cut and paste the file name into the obj. text when needed. I don't know if my not using any underscores was causing a problem?

I think I understand how the obj. and mtl. Files work with each other, and that I have to use the same object name between them, but can the file name be something different? Can I use ‘Structural Brace with Light’ as the file name, and eventually what it’ll be listed as in SH3D, if I use ‘light’ and ‘brace’ for the internal file purposes within those files?

I don’t understand how the files work together. When I bring an item into Furniture Library Editor, is the program only drawing on the data stored in the SH3F file?