3ds max Modeling with the Symmetry modifier Now we'll add the open subdiv modifier and because the symmetry is welding the seam, we won't get any seams here when we shape our model. Go into the modifier list and add an open subdiv. Increase the iterations to two and now we've got a rounded box. If we go back down to the editable poly and enable Show End Result and go into Sub-object Vertex mode, we can see an overlay and if the color of the object makes it difficult for you to see these elements, you can change the object color. I'll set it to a light green color and that's giving me better contrast so I can see these orange edges and blue vertices. So, I can select a vertex or vertices and then transform them using the move tool. And as you can see, we're getting a soft result. So, subdivision surfaces are working quite well. Now, we do have a little bit of an issue if we want to work on some vertices or sub-objects near the seam. If I select one of those seam vertices, and move it, then we'll get a gap. I'll undo that with Control + Z. So, as you work that may happen, you may end up with gaps in the model. Also you may want to scale edges or vertices and scaling can be problematic at the sub-object level, so I want to show you a little bit of a trick for that. I'll undo that last movement and I'll exit out of Sub-object mode. And just for clarity in the view, I'm going to isolate that selected object, enable Isolate Selection and let's say I want to scale in the top viewport here and shape the edge loops, so I'll go into Edge Component mode and double click to select an edge loop and we can toggle around and we can see that we've got all of those edges selected and again, if it's difficult to see, then maybe change the object color. Maybe I'll change it to something else entirely like magenta. So, there are the selected edges highlighted in yellow and if I want to really verify that, I can disable Show End Result, so there are the selected edges. Now, I want to scale these, so I'll turn Show End Result back on again and in Edge Selection mode, grab the Scale tool and notice where the scale gizmo or manipulator is located. If I try to scale in the x-axis in the top viewport, then I'm going to have a problem because my edge points along the border here are going to move away from that seam and we're going to have problems. So, I'll undo that with Control + Z once again and to fix this issue, what we want to do is preform all scaling and maybe even rotation and move operations relative to the current object's pivot point
