Expose Terrain Material Layer from blueprint

I have the below play area and I have 4 terrain materials defined in a material and attached to the terrain. What I want to achieve is a way to use a blueprint to expose the pathway layer through the entire maze while avoiding collisions.

Terrain Sample

Terrain Material

This is what I wanted to achieve programattically via a blueprint with the path. By collision I mean it cant go through trees, rocks, bushes or walls with colliders on them.