There is such a tool you can buy pre-made - ah yes, I think it's called a Flare Buster. The only problem is it's so light, any breeze may make it wobble...

I've frequently run into situations where my lens hood isn't enough and I need to hold out my baseball cap to shade the lens.

Then the other day I wanted to get a shot of some storm clouds, but it was spitting rain and I didn't want to angle my lens up into it.

So now I'm thinking of making some kind of a card on a wire that I can attach to the camera or tripod and angle out for shade and shelter.

Has anyone made such a tool, or used the Wimberly Plamp or variations in such a situation?