Rib Feature: A specialized feature used to create structural supports (ribs) on a part, essential for injection-molded plastic or cast metal, often saving material while adding strength.
Fillet Feature: Adds a rounded, tangent transition to corners to reduce stress concentration, improve aesthetics, and remove sharp edges.
Chamfer Feature: Creates a beveled, angled edge (45° or 60°) to make assembly easier, remove sharp edges, and aid in machining processes.
Why use all three? They are crucial for moving from a "beginner" model to a "production-ready" model.
