Back in the "good old days" you would insert a very expensive film cartridge in your Polaroid camera and the excitement would start when this cover popped out of the front. You then knew you had ten possible pictures to fascinate your friends instantly. It had a battery in the film cartridge and focussed by sonar, so felt very sophisticated.
Later it was found that with a ball point pen could manipulate the picture if you did it quickly after the photo popped out. I used to buy Polaroid's just to manipulate them, but stupidly they developed a new formula that did not allow this; so no more Polaroids for me.