Eye Material?

I've tried out a few different methods making eyes and none of them are very sturdy.

For the whites of the eyes I've been using some bowls I got from the dollar store. While they do they job, they aren't completely opaque and they're pretty flimsy, and I'd like a plastic that has both the curvature, full color, and rigidity I need. I'd use those other bowls people use but I'd prefer to use the actual material, whatever that is. The ability to paint it different colors would also be a bonus. Using the foam sheets isn't something I prefer doing for the whites.

Regarding the iris / see-through part, I've been using a fine buckram, and again, while it does look nice, it tends to warp easily, and again I would appreciate something sturdier. I had used plastic mesh for a while but the holes are a little too big, but I might turn over to that later if I can't find a good substitute.

I'm also looking for better coloring methods to use on the eyes, paint pens work fairly well but they are pretty expensive.