What is the best method to precisely select polygons for extrude in zmodeller most methods have fuzzy border

#1

hi
what is the best method to precisely select polygons for extrude in zmodeller most methods have fuzzy border
in example default qsphere tried to mask select 2 polygons for extrude, all methods seem to give
more than 2 polygons

please see attached:https://www.flickr.com/photos/93465359@N03/45959410234

thx

#2

In ZModeler, hold down the Alt key and click on the polygons you want to extrude. The selected polygons will turn white. Once you’re finished selecting polygons, release the Alt key and then click and drag to extrude the polygons.