FOSS gamedev and creative worlds

I'm currently working on a mod with flying structures (based on technic's frames mod but without frames and limiting the structure to connect by frames only). Any nodes can be connected to each other by metadata, and I need to see by punching them with a tool what nodes are connected to which ones. I need some way to highlight a set of nodes. How can this be done?

My only thought for now it making some entities in the air pointing to the nodes that auto-destroy after few seconds. But maybe there is a more efficient way?

Could you add light_source to the nodes temporarily?