Sunshade/Sunshield for IPC-HFW4431R-Z?

It seems like the whole diameter is to big.
The whole diameter for what? The PVC tube is a perfect fit for this particular camera. With the little bit of a seam where the glue joint is I actually have to apply to some pressure to get it to go in, and then it's pretty darn secure.
 
I'm referring to the picture, when the camera is on a pole. At the bottom it looks loose.
 
Ah, that. Yes, there's a little bit of play in that application. The profile of that camera isn't a cylinder; it's a rounded rectangle, so it will never fill a round tube. I have it shimmed up so that the tube actually points upwards a tiny bit. That actually helps with the IR reflections at night.
 
What I was saying, if you cut a slit there, and put a hose clamp around the whole tube, it will close the gap and would tighten over the camera.