I want to try to make dosa. I got a flat skillet similar to the kind in
the indian food stores, and I bought some of the mix for practice.
Unfortunately, the mix had bugs crawling in it, so I had to toss it. I
see a ton of different ways of making it on the Internet. What has
interested me so far is how many rely on cookied rice. Is this
something people make with their rice leftovers?

Assuming I have multi-purpose flour, wheat flour, maida flour, medium
grain rice, and basmati rice, how could I make the dosa batter?