I've created the multipatch features through the " interpolate polygon to multipatch" tool, and the original data came from a raster that I reclassified.
What I'm trying to accomplish is to show the actual depths of the glacial ice throughout the glacier in 3D, I want to make my multipatch extend from the surface to -15m below the surface of the DEM, so I can visually represent it as well as determine volumes and estimate the topography below the ice. Instead of dragging the multipatch downward from the green ball that appears for that action, I'm looking for a way to evenly extend the multipatch features, so they extend exactly 15m below the surface of the DEM. Hopefully, that is a little more clear.