afterthought: As much as I said “use zero at top” I realize you can create a pretty cool effect with “zero at bottom”… skip the whole regular 3D carving paths (step 1 and 2) and in Carbide Create, do a “zero at bottom”. But in Carbide motion, you zero the machine at the top.
What this will do is basically only cut into the material the shape you have, exposing the 3D carved relief, while leaving all the places you don’t cut as is…