https://timeoftheworld.date/wi....ki/Cat_Flap_Installa
https://opensourcebridge.scien....ce/wiki/How_Much_to_
Installing a cat flap on your door's panel is an essential task that should be carried out by an experienced professional. The doors are typically made of a plastic exterior that is bonded to an insulation-enhancing, soft polystyrene base. These materials can be difficult to cut. It is much simpler to install the cat flap inside an existing glass pane, or to make the hole in a new door. A glazier can do this for you. Easy