I created this backlit box on my resin 3D printer. It’s a memorial box for my grandparents and has a small candle light in the center which is used to illuminate the images.
This is called a lithophane and it is a process in which you convert a flat photo to a 3d model. The dark areas of your photo need to be opaque (preventing light) and brighter portions need to transmit light. We’ll it so happens that semi transparent materials such as resin or plastic and even very thin wood - can block or somewhat transmit light. To block light you make sure you have a thickness adequate to do so and the thinner the material is the brighter the backlit image becomes.
So how do you convert a photo to a lithophane?
Just search for the term “free lithophane” and you’ll find a plethora of online tools which allow you to upload an image, and at the end of the process you can download a 3d model. The resulting model is 3d in the sense that the photo was converted to black and white and then the brighter areas are thinner that the darker areas (In the Z dimension). Because you will produce this in a very thin sheet (to retain the permeability of light passing through) you will likely not be able to see these bumps when examining your printout of the model but can probably feel them if you run your finger across. Here are a few examples from an online search:
once you have the 3d model downloaded print it on your 3d printer or carve it on your CNC out of a veneer or thin opaque acrylic. I produced four flat panels for the above product and then printed a box with slide in holders into which these panels are inserted. I added a bit of CA glue and viola!
Here are a few tutorials to get you started:
1. Producing a lithophane on your shapeoko CNC
2. Producing color lithophanes
3. Creating lithophanes on a SLA (filament) 3d printer