I've done my fair share making cosplay pieces and armor from foam, worbla and even some 3d printing. I have just landed my hands on a good full wearable set of the SRT-1 Barracuda Iron Girl Armor based on concept art by Bogdan Gabelko and modeled by Johan Jaoa. The suit is wearable and beautiful BUT I wanted to separate the cod piece from the torso and then either print/mold/cast the torso in a flexible medium or just print it straight in TPU. [Breathing is good!] This would be a one off just for me. I am a complete noob when it comes to any 3d modeling software and have never separated pieces along an irregular line. I tried using MeshMixer to separate the shells but they don't come out to anything remotely usable. I tried using the knife function in Blender but I can't seem to get it to work. I've provided pictures below for reference on where I'd like to cut. Suggestions, ideas, anything would be greatly appreciated. I want to learn HOW to do this so that I can keep doing it in the future if (when) it inevitably comes up again.