Taking a look at methods for cleaning up the almost “left over” faces when extruding, Jamie Hamel-Smith provides a couple of specific examples of where you would get extra polygons with the extrude tool in Cinema 4D, and how to address the issue.
creating an extrusion (inwards) near the edge of a cube—what do we do with the extra polygons, and what’s the easiest way to accomplish this?
Jamie notes that there is no real instant solution, but does provide a couple of tips and shows how he chooses to solve the problem in his own workflow. Check out the tutorial for Two Basic Extrude Tips in Cinema 4D here.
