So, I wanted to see if I can machine a Lithophane. Problem was I did not have the recommended Corian sheet or similar translucent acrylic. Well, and I do not have PhotoVcarve either.
Here is a method that provided a pretty reasonable result (not sure if that is a newish idea or already known):
I used this image of my toy car to start:
Imported into the Windows 3D-Builder (comes with Windows10), and converted into an .stl file as height map with highest color resolution and medium high pixel resolution:
Imported the .stl into VcarvePro as model and created roughing tool path (0.125" dia EM) and finishing tool path (0.05" dia ball end):
Then started cutting on my machine (roughing about 12 minutes and finishing about 55 minutes for an 8x3" result. This is clear extruded 0.22" thick acrylic and I broke 2 bits before I got the feed and stepover right in this sticky melting material. I did use a pretty hefty compressed air stream (from the aluminum tube in the picture) to clear the swarf and cool the bit.
To be continued...