Sure Flap large cat flap external cover

We have serious issues with draughts through our Sure Flap cat flap in the winter - historically I would build a polystyrene plug for the cat door, but it was never a very good fit. Our flap is the large version of the flap - we've had it a few years, but I think it is most similar to this one (please do your own measurements). https://www.surepetcare.com/en-gb/pet-doors/microchip-pet-door This cap is a quick and dirty remix based on a model for a compatible extension tunnel found on printables. The cap sits over the exposed outer portion of the cat flap tunnel. www.printables.com/model/1473508-tunel-for-grande-chatiere-sureflap Important, it doesn't plug the inside of the tunnel, it fits around the outside, so if your door is too thick to leave the tunnel exposed, this will not work for you … however you could scale down to form a plug. There is room for improvement in wall thickness, filleting etc. it printed in about 3hrs 20 on a P2S in PETG (since it is living outdoors subz