Replace Tool

Use the Replace tool in the Edit ribbon group on the Design tab to replace one face with another. You can replace multiple faces with a single face, replace a single face with multiple faces, or replace multiple faces with multiple other faces.

The Replace tool also lets you manually simplify or align complex faces and curves into planes, cones, and cylinders. (If you want to automate this process, use the Simplify tool in the Adjust group on the Repair tab to automatically find problem areas.)