Cheap plugs
I made mine out of the kneeling pads you buy in the local garden department. Cost is about $5.00. I used a yogurt cup as a template to draw a circle on the pad and then trimmed to fit with a bandsaw. They fit snugly into the small holes in cowling very nicely. I used a piece of cardboard to make template on oil cooler opening, and then cut out of same kneeling pad. They work great!
