I've seen the tutorial for upside down icing round layers and also have seen the video post which is fabulous...YouTube is full of the "hold your spatula where you want your corner and build a dam of icing" videos which are very informative and I love, but...

My question is: Does anyone know where I can view an upside down tutorial or video for icing SQUARE cakes? I've seen awesome work here and I can ice a square cake cleanly, but dagnabbit...

I want those crisp edges