Welcome to the forum. I briefly opened your part. I don't have much time to spend on it right now; someone else probably will. I just wanted to mention that this would be a perfect place for you to create a sketch of your mold profile and save it as a .sldlfp file. You could then use it in the Structural Shape feature on the Weldments toolbar to create the molding and it will automatically miter the corners. If you're going to be doing much of this type of modeling that would save you an incredible amount of time.