The bottom of my lower window sash has been effectively "sanded smooth" by my dog's paw nails after years of her looking out the window. Any ideas on how to restore to match the profile of the mullions?
If the dog is still alive and damaging the window, I wouldn't bother repairing it yet. However, if you wish to try to build up the damaged area, I would try this: create a negative profile of the the decorative egde buy applying a hunk of epoxy putty onto a good section of the edge. You will want to either wax or spray on a release agent to assure that you can remove the profile from the edge. Use the resulting mold to force sandpaper along the edge to be repaired. Build up the edge first with an easily sanded acrylic wood filler. It probably will take two or three coats to build up the area. You probably should sand after after each application, slowly building up the profile. sliding the profiled sanding block along the edge should give you a good reproduction of the original wood. Of course, this anticipates that the wood is painted. Some of the wood fillers do claim to be stainable, but in reality, they will never completely match the original wood grain.