Chopping: The Right Way to Do It

Hello everyone,
Recently, we had a discussion among colleagues about the topic 'Let's remove the roof.' Shortening the body from the top is not a major problem from a metalworking perspective, but what do you do with the windows?
Are there specialists who can custom-make lenses? Or are there specific cutting methods, such as waterjet cutting, used to trim things?
Does anyone have any ideas?

Greetings from Harald in Wiesbaden .