.. knock out plug removal from v/c ? ..

I had some NOS M/T covers a few years back, took a punch and whack the plugs out. Thought about drilling but then looking really close at them, I could see the metal was a little thin around the plug covers. One good whack got most of the plug out. I laid the cover first on some wood and just held it steady and wham, out the little piece went.

Wait, I believe I hit them from the inside of the covers and had the end of the cover past the block of wood. Look like it come out cleaner that way then driving it in to the cover. The little bit left I just filed away by hand. Put one breather on each cover and just remove the breather to add oil. No oil cap, thought it look better that way. (how often do you add oil)