OLEO - Came in a pound plastic bag, and had a red button in the center part of the bag. You had to pinch the red button, to puncture the inside of the red button. This released food coloring into the white oleo.
I remember having to squeeze this bag for a long time, to get the food coloring all through the oleo, to turn it all yellow. It was unique and interesting at first, but got old soon.
As I recall the dairy industry put up a fight and would not let them sell yellow margarine, thus, you did the mixing yourself. I think I remember when we got our first package of yellow oleo, in 1/4 sticks. I think this all happened during the war, early to mid 40's.
Pliofilm, developed in 1934 by the Goodyear Tire & Rubber Company, was a rubber-based clear (and later dark green) plastic. I think there were some health concerns about the Pliofilm. I think my Dad's '49 Cadillac had clear seat covers make out of Pliofilm. Even some health concerns when they used it to package the Oleo.
