We found these cool books while shopping with my parents and sat down to flip through them.
"Rach! Hold it up to your face like this and you can see the images pop out!!" I said.
"I know! I can see a star reaching out to me! This is SO COOL!!"
"Wow! Mine is reversed on this one and the image goes in instead of pops out!"
And that's pretty much what we did for the hour or two my parents shopped in Costco (my dad likes to browse).
People stopped by, observed our behavior, and picked up one or two of the books and added them to their carts.
We convinced our parents to buy them for us.
When we checked out, the cashier said something like, "Wow! These 3D books are flying off the shelves today."