Fill the boxes with a gift or secret note. Seal them up or keep the tops open. Try adding cording through the top and hanging them.
One of my favorite things about this project was the layered tissue paper. You can use this technique for other paper projects. Find a high-contrast background paper with an interesting image or pattern. Black on white images work really well for this. Decoupage a layer of tissue paper or light weight decoupage paper onto the top. If the tissue paper has large light areas, you will be able to see the background layer through the tissue layer.
Use any thick clear plastic for your reusable scoring template. I like using clear thin mounts for stamps. These are durable enough, yet thin enough to cut through. Also, they are fairly inexpensive and I usually have several lying around!