polystyrene

[tinadog]

what is the best tool to use to cut polystyrene

[m.b.kid]

blunt jack saw or bread knife:)

[matt1e]

brings back memories of when I was an apprentice
We did a rewire at a polystyrene factory and they use to cut it with what they used to call A "hot-wire" which basically what it was

[heathfield]

DIY hot wire cutter.

[wildwood]

But if this job is just a oncer, one of those snap-off knifes will do nicely. Let the knife do the cutting without pressing too hard, if you know what I mean. You'll probably have to make several passes to cut it cleanly, depending on the thickness.