To make a simple foam picture frame that kids especially love (I made mine as a kid and still use it to this day), you’ll need two foam sheets of differing colors. They are found at any craft store. You may also want decorations to add to the outside of the frame. They can be flowers, jewels, or anything that interests you.
Cut two rectangles, roughly 7x 9 inches so they fit around a standard 5×7 picture.
Cut a rectangle-shaped hole from the top foam sheet roughly 1 inch from the outside. Hot-glue it to the bottom sheet on three sides.
Hot glue all the decorations onto the outside of the frame.