Lithography holder

I though it would be a good idea to make a kind of "lamp" to hold a Lithograph, as a Christmas gift, so y designed this one wich only requires four LEDs, a Battery holder and a switch.
This thing is made for a 5mm Thickness and a width of the image of 100mm. The aspect ratio can vary as long as you keep the 100mm width of the lithography (maybe it can be used to hold any kind of image wich width is coincident, but I don't think that would be a good idea)
The circuit of the make is explained in