Munsters dragula

[Frankieboy]

Hello y’all.   Just joined today.   I’m building the AMT dragula car.  How do you cut the top off of the coffin?   I seen a build of that model that was painted purple on the inside with the lid open and the bubble cockpit glass hinged back somehow.  Maybe the guy who built it will chime in.   I’ll see if i can find a pic of that.  Haven’t built models since I was a kid. I bought a few boxes of models at a garage sale. The dragula was in it.  Thanks yall