Diana 5 foresight rubber cover

I enjoy collecting and rebuilding Diana air pistols. One of them is in like new shape except for a torn foresight hood rubber cover. There are no spares to be found. I was thinking that some enterprising individual may have found similar tubing and made their own. If someone could provide that information it would be of great help.

Here is a link to a schematic of the pistol. The part I am looking to replace/create is OS002

https://www.gunspares.co.uk/products/24392/5