A lithophane is a 3D depiction of a 2D photograph. The black and different grey-scales are represented by different heights of printer material. The artistry is visualized by shining a light behind it.
The stand I designed will fit a curved lithophane with an arc length of 75 cm (ie. the curved width of photo). You can use a LED light on incline platform to shine light on lithophane. The more diffuse the LED is better. If you get a uneven light source I found that using a white 3D printed part to place over the light helps.
I have illustrated the process with a photo of Einstein. I use the link
to generate the STL file. My example image was W7.6xH9.57 at 300 dpi. It does not matter if the input image is colour or greyscale. The settings I use are
Thickness 2 mm
Thinnest layer 0.8 mm
Everything else are default settings.
Use outer curve, Whenever you change a value please refresh.
Hit download to bring up dialog box. A file name with nameofpic.jpgWxxH100...... .stl pops up. The xx in the name of STL file is the arc length and 100 is the percentage. Note the value of xx. The actual percent you will need to reduce your lithophane to fit the stand can be calculated as being equal to (75/xx)*100.
Now cancel and include the % value calculated into Model settings, refresh and generate the new STL. Remember if you scale the model the arc width and thickness will change.
Slice and print. I use Cura and print vertically at 0.15 with a brim for support.
The higher the infill percentage the better. I used 15% and 100% and unless your printer is working optimally the top layer of the platform will not be perfect. I used 15% in mine so not perfect but for model 2 I used 100% which is great. You will get some imperfection because angle but not too bad as the LED source will cover it.