I cut this 10"x12.5" (actual cut area) Lithophane without a roughing toolpath on .25" corian using a 45 degree V-bit!
I took the picture of this huge sculpture/waterfall at the Jackson Rancheria Casino in Jackson California yesterday.
I have attached the PhotoVCarve cutting parameters page, as you can see I told the software that I am using a 0.031 ball nose bit.
I set the Z zero at -0.1" and cut it in one pass.
Cutting at a 45 degree angle is essential with this method as it is a deep cut.
With the V-bit once the first pass is cut each subsequent pass is only shaving the edge of the previous pass.
This is why the roughing pass is not needed.
Pine Grove, CA