Of interesting note. - The solid and void are inside of a Generic Model family where I am running the script. - if I leave the family editor and run the script on the family that has been inserted into a project, I do get the correct centroid. The final cut geometry is recognized. - That is good, however, I would like to be able to run the script within the family and insert a marker for the centroid there… Perhaps there is some way to run it at the project level, find the centroid, and then insert the centroid marker into the family in the correct location in the background? - That would perhaps be even better, but I was trying to take baby steps… I would actually like to account for materials too as some solids might be concrete, some steel, and some insulation, or other materials, all with very different densities. - some will be nested families too… again down the road, just trying to figure out what is going on with voids would be enough for now.