re: How to get crisp fondant edges on a square buttercream cake .

Ahh I guess I didn’t read all the way to the end. oops

Here’s an idea. https://www.youtube.com/watch?v=nbU5O1YRjBI
I’ve also seen some blogs where they use these to get a nice sharp edge. http://www.flourconfections.com/advanced_search_result.php?keywords=edgers&osCsid=06a462a93b711eeaa534a62315f0ef0c