Well I certainly learned a lot from looking at your blueprint! I also stumbled across being able to double click a static mesh component in a blueprint and being able to move it individually - that was the missing link for getting the bounds size as I drag, I think.
One thing looking at your blueprint, I can see that you are using the ‘extent’ variable to set the locations of the corner meshes, but there is nowhere that variable is being set? Do I have the whole picture?
Thanks for the info! Back to the drawing board…