Okay, the blowtorch thing made me laugh (something I always appreciate).
I was trying to decide between a coping saw (even though they're a bit difficult to cut straight with), and just slowly cutting through it with an Xacto and a ruler. The file seems a logical step, and I was thinking of working with plexiglas or an acrylic picture frame as raw material in the first place.
Sadly, I haven't got a blowtorch, and don't really have a place to keep one at the present time, but some day ... (dreamy reflection) ... some day.
Do you think a heat gun would do the job? I have one of those already.