It's a slide box, and the cover doesn't open.
The instructions are 100 dpi. Print the box pieces out at 300 dpi on card stock. It takes 3 sheets of card stock to make one box. Click on the images for the full sized versions. Finished box is just over 3 inches wide, 4 inches tall and 1 inch deep.
I used a photo of forget-me-nots I took last summer into Paint It! (affiliate link) which is 11.50 on Amazon right now. Paint It is limited, all it does is painted effects on photos, but it does a very nice job on that.