then cut the straight lines with a hacksaw blade. This took me a couple of hours start to finish.
Just an aside, have you discovers the tungsten carbide hacksaw blades? Not the ones that are completely round, but the ones that look like a wide hacksaw blade that's edge has been dipped in glass shreds. Like this:
http://cgi.ebay.com/REMINGTON-HS10C-TUNGSTEN-CARBIDE-HACKSAW-BLADE_W0QQitemZ4391725871QQcmdZViewItem?_trksid=p3286.m20.l1116
I bought two really high grade Sandvik ones ($20?) a few years ago, and it's the best wood, plastic and soft metal saw I've ever used - it just glides through plexiglass, maple etc. It might take like 20 minutes to do the above job, not cutting is harder than cutting with the thing. I still haven't got to the second blade, the first one shows no wear.