This seemed like a futile thing to look up but every single guide I check seems to work for a different use case. My question is this: given a "prism" (or just an extruded rectangle), how can I outline it with a thin black line? Below, I attempt to apply a stroke but it just changes the entire outer 3D edges.
What I actually want is this (made in PowerPoint):
How can I do this in illustrator?