LithoBulb: Free tool for 3D-printed photo spheres

Lithophanes are one of the established applications in FDM 3D printing. They use the varying light transmission properties of plastic to make images visible by varying wall thicknesses. Until now, this principle has almost always been limited to flat or slightly curved geometries. With the concept of so-called LithoBulbs, this approach is now being transferred to a spherical structure.

The basic idea remains unchanged: areas with greater material thickness allow less light to pass through, while thinner zones appear brighter. What is new is the spatial implementation. A LithoBulb is printed as a closed sphere and illuminated from the inside with an LED light source. The image appears on the outside of the sphere and changes depending on the viewing angle, as only part of the surface is visible at any given time.

Mike Lejeune provides a browser-based tool for implementation, which can be used to create LithoBulbs without additional software. Users create a collage-like composition of images, text, and simple design elements. A square layout with 4000 x 4000 pixels serves as the workspace, from which a printable STL file is then generated. According to the description, all functions are available without restrictions.

When designing, it is important to bear in mind that the spherical shape limits the display. Only a section of the total surface area is visible at any given time, which influences the selection and arrangement of the motifs. The tool offers numerous parameters for adjusting the conversion of image data into wall thicknesses. Presets for common LED configurations make it easy to get started, while additional controls allow fine-tuning for different light sources and brightness levels.

The generated STL model represents the outer surface of the sphere. The actual image effect only becomes apparent after printing and installing the lighting. Without light, the surface appears inconspicuous, but with the LED active, the motif stands out clearly.