Our Christmas card from a few years ago.
The card mechanism is very cool. It’s called a dissolving card or a pull tab changing picture card.
The start position.
Pull the tab and it changes to this picture.
Here’s how it’s made:
There are four interlacing slat pieces, two per picture.
Once they are properly stacked, they are secured in a frame.
Here are more comprehensive directions (not mine) for a similar card. This card mechanism is also included in the book: Making Mechanical Cards by Sheila Sturrock.