Cessna Cardinal 177 Fresh Air Intake Plug

The most basic plug for the fresh air intake hole on the wing of a Cessna Cardinal 177 (1968-1969 wing). 

Printed with TPU95A, but any TPU would likely be good to have the flexibility and snug fit you want.

Obviously this is not hard to draw in CAD, but it will probably save you a trip to your plane with your calipers to get the measurements.

The model has a gradual tappered so it can't fit all the way in and it wedges in snuggly with a firm push with your hand.

It includes a slot to loop a 1" wide piece of webbing through it. You're welcome to be more crafty and sew the webbing so it can't come back out or just go simple and tie a knot (I used a Figure-8 which creates a pretty bulky knot when done with webbing).  

I might change it however as the length of webbing I have will flap in the wind and the knot on the end will beat on the plane a bit if I park outside while traveling.