Using the preview window is about the only thing that will work. I have asked for a function to lock a polymesh but based on how the current bug report/feature request list is being handled I have little hope of this being considered. Of course the preview window is small, and does not maintain size after re-sizing (if you are in the habit of changing rooms for a better look, say). Oh, and don't get too careless around hidden objects. Sometimes just to be ornery Carrara WILL perform operations on those hidden and presumably impossible to select objects. I have had this happen enough times to where I generally avoid using the hidden function at all. Never happened in Carrara 3, but that's progress for you. Still, the method does work. You can get a pretty good idea of what a shape is doing with peeks in the preview window. Actually, is simplest just to keep the model you are making in a new instance of the VM, and never have the body you are fitting to in the same room at all.