A lithophane is a photograph that is 3-d printed using only white or ivory plastic. In normal lighting, it doesn't look like much of anything, but shine a light behind it and the image comes to life, as shown in the gif above.

Your photo would come with a wooden LED base that would display it lit up. Such bases can also be used to light up laser-etched acrylic cutouts, as shown in the photo below (which is not mine). That is also a service I can provide.

Colored LEDs will light up a clear acrylic sign in the color of the LED:

I can also make spherical lithophanes, like my "Venusian Dragons" creation here: