OK, ladies and gentlemen, put on your Thinking Caps...
 

And come up with a Cheap-Ass alarm.

On the Mazda, I don't want to go to the trouble or expense of installing a
real alarm, but I want something.

Honking the horn and flashing the flashers would be good enough. I want
the horn to 'beep', so a flasher unit and a relay or two would be good.

There's two ways to set the thing up:

Put something like a key switch under the fender, turn on when leaving,
turn off when using the car.

Or, a little more sophisticaed: put a switch inside the car. Now, this
would mean triggering the 'alarm' when getting into the car, something I
don't want to do at 1 AM when I'm leaving on my 'paper route'. So, some
kind of delay would be good. I was thinking a capacitor between the hot
line and the 1st relay, so the cap charges and when it reaches charged it
triggers the relay and starts the flasher.

But, I need a hint what size cap to use, and how to wire it into the relay
so that it charges before setting off the horn, maybe 20 seconds is good.

Of course, we could get REAL sophisticated and use the ol' venerable 555
timer, but that's more involved than I want to make it.

Any ideas?