Does anyone knows what they called? , the picture frame or the method that makes two pictures in one picture/frame. I saw it at the booth in front of disneyland and universal studio. There is one frame, but if you look at from the left, it shows one picture; as you move more, it shows another picture. Ive seen that kind of trick long time ago in many toys; but I’m thinking of making my own. I tried to search on the internet but had no luck. I just did not know what’s the specific term to look for. 

I think you’re thinking about a lenticular image.

yes ; that’s the one. Thank you. :D