I would like to measure the angles between these faces to make a model. The problem is similar to this topic, but it seems to be unsolved. Any help is greatly appreciated.
Measure Face Angles.gh (7.2 KB)
Text panel shows angles in degrees between each pair of adjacent faces. Would be interesting to make sure all the face normal vectors face out (or in).
P.S. In addition to that, I made a fundamental error in version ‘a’ so replaced it with version ‘b’ below, including a pair of linked ‘Tree/List Viewer’ tools, where the tree slider (‘path idx’) on the first copy is wired to the second copy, so both show the same branch of different geometry trees. The first one shows edges (piped for the selected branch, from BBX result) between adjacent faces shown in the second ‘Tree/List Viewer’.
The ‘path idx’ slider is set to branch {0;14;0} where the ‘Angles’ panel shows zero degrees between faces 14 and 15, which looks correct, eh? 
Face Angles_2024_Jul15b.gh (49.7 KB)
I didn’t use the PFrame and circle on each edge but left them as food for thought.
P.S. On third thought… Are angles between face normal vectors the same thing as angles between adjacent faces? This method ignores face normal vectors and instead uses those circles and the PFrame used to create them.
Except for some supplementary angles (adding up to 180 degrees), the results are the same.
Face Angles_2024_Jul15c.gh (47.1 KB)
Thank you for the multiple solutions, also the reason why all the face normals are not facing out or in is because the entire model is a möbius strip.
I can see that but… it gets weird and confusing. This version (‘16a’) uses uncorrected face normals, showing angles in the first text panel. The second text panel shows angles from the “circles method” (included). The third text panel shows angles from the corrected face normals (all “out”). The only difference between the first two text panels is angle 3 (between faces 3 and 4), and the two (119.41 and 60.59) are supplementary angles (adding up to 180 degrees).
So the angles between adjacent faces depend on how you look at it. 
Face Angles_2024_Jul16a.gh (56.1 KB)
These are also great, thank you.
These are the same as before, I only deleted the bits that chose the outward face normals.
I thought the third one was new, but thank you anyway.