Removing a front-installed flat front crystal

I bought a rectangular watch to gut and replace the face – I had hoped the face/dial wasn't sandwiched between the case and crystal but based on what I can tell, it is. Not 100% sure why they made this decision, but whatever.

How do I remove the crystal without cracking it? It uses a white gasket. I can take some photos later, but is there a general procedure for this?

I can 3D print a rectangle that fits the inside perfectly, but the last time I tried this with a watch it bent the dial metal.