Your help is valuable, but this statement is incorrect (perhaps a typo left out the word “not”?). SketchUp is a surface modeling program. Every model is built of planar faces and edges. Inside a closed surface made of faces there is nothing, and two closed surfaces can pass through each other without interacting. A “solid” in SketchUp thus does not have the behaviors most people (and other apps) would associate with that word.
But in addition, unless edges and faces are isolated by putting them in a Component or Group, they are not considered to be separate things. They all stick to each other as one unified collection. Without seeing @wowrs’s code and a sample model I can’t tell you why some of your openings provoked the SketchUp GUI to fill in faces and others did not, but the root cause is that the bits are not isolated from each other.
Using groups (or better, components because your structure has many identical parts) is certainly the solution. But you need a group for each collection of faces and edges that corresponds to a complete object in the model, not a separate group for each individual edge! Perhaps thats what you meant and the wording just wasn’t clear…
Using the GUI, by drawing the edge, selecting it, and then creating a Group from the selection. Using the Ruby API, by adding a Group to some Entities collection and then invoking add_line on the group’s Entities. There is nothing that prohibits a Group from containing just a single Edge, though such a thing is of pretty limited usefulness.
is it only to make the single edge available in the outliner? If so…why is it not included in the context menu?
The reason I ask is, I created a cube, opened the context menu, used “select only” all the edges, opened the context menu. Selected make group (which was now there) made a group. it appeares in the outliner. then attempted to select the group and it doesn’t select any group the way it normally would. Is that because it was touching the faces when I tried to create the group?
Now I hid the faces…selected all the edges and made a group in the context menu. Attempted to select a group and it only selects a single edge.
Entity info only lists entities…not groups.
Outliner shows groups.
the groups are not selectable outside the outliner.
I can think of two things that may be confusing you. First, since a face can’t exist without its edges in the same context, when you selected only the edges and created a group, new copies of the edges were made within the group’s context and the originals were left in the model’s context as boundaries of the cube’s faces. Second, to select a group in the GUI you have to click on something that is unambiguously part of its contents. But in this example because there are matching edges both in the model and in the group that can be tricky. The GUI seems to prefer selecting the model’s edges rather than the group. But you can select the group in the outliner window. Or you can drag a selection around everything and then use select only groups.