Model generated from SVG illustration using paths2openscad (based on Dan Newman's Inkscape to OpenSCAD extension). SVG derived from pen/marker doodle with the Adobe Shape CC app. I did forget to flip the model before printing, so the stamp produces mirror images of the original.
Tested with PLA and India ink. There may be better material combinations. It took a number of stamping attempts before a clean print was possible. I think the surface layers had to get saturated with ink first so that it wouldn't just run off.
Anyway, it pleases me to pull a picture through the full circle of ink to various digital and mechanical representations back to ink again.