Just got paid, so I'm going to start looking at sandpaper and muffler repair kits that include epoxy resin. Still going to pursue the poor-man's anti-theft plan here. In the meanwhile my old buddy Tim, who was a safe cracker for a locksmith (an honest, law-abiding citizen his whole life, I might add) had this to say about my plans regarding AUTOMOTIVE specific cats:
He imagines that if one were to take a piece of 3/4 inch steel bar stock, cut it in half with a bit of a diagonal cut, take it to a place that does heat-treating, then have a muffler shop tack-weld it to the top of the exhaust pipe with the slightly angled ends snug up against the cat, he said that a determined thief would have to cut the pipe quite a distance ahead and quite a distance behind it if he didn't want to be there a while sawing away at a piece of hardened steel bar stock.
Tim also said that up in the Cleveland area there seem to be quite a few places that'll heat-treat a piece of steel for just a few bucks if you ask. He imagines this might be true of other major cities. Same with muffler shops. He says if they understand what you're asking, they'll probably do it for you for a few bucks. They'll almost certainly not warranty the work, but they'll probably do it when they understand you're trying to repel thieves.
So, if you can weld or have a muffler shop nearby, and you know a place that does heat-treating, here's an idea that could help you hang on to your cat.