Construction Script That Changes MPC When BP Box Overlaps With An Actor?

I’d like to create a simple BP that will automatically turn a material parameter for an actor on or off if the BP box is coming into contact with that particular actor. More specifically, I want to be able to drag the BP actor box out onto an area of the level, and for any static mesh actor that the box touches, it changes a parameter from 0 to 1.

I understand MPCs and materials and have that set up, but I’m very new to blueprints. I want to be able to do this in the level editor itself and have it be persistent once the game starts. You may have to ELI5 on this one. How would I go about doing this? Thanks for your help.

I got it to work! MPC wasn’t the answer at all: the Use Custom Primitive Data flag was. Find the object, find the BP box, compare extents to see if they intersect. If yes, set the CPD to 1, if no, set it to 0. Voila!