Hello,
check done with the 3d printing toolbox shipped by default with Blender (File > User preferences > Addon > type “print” in the search field, check the 3d printing toolbox addon, then select your object, left side open the 3d printing toolbox tag, hit “Check all” button), here on blender 2.79 (because I do not need to run the software GL variant on this old computer):
Generation was done with a locally built 2.9.5 prelease gmic-py
I can rotate the mesh 180 degrees on the x axis, the that the relief looks up on Blender’s z axis, and scale it 10x or 100x smaller so that it fits better on the scene workplane.
There is nothing non manifold, no double vertices, no holes, the non-flat face is here (enter edit mode (tab), face mode (ctrl+tab), click “Non flat face button” in the left pane to have it selected, then the “.” numpad key to focus on it) and nobody cares about it:
The overhang faces statistic is not important, when clicking the related button in Edit mode > Face mode, one sees they correspond to the bottom surface’s faces.
Despite applying a Shade smooth:
The mesh looks very non-smooth… because there are hundreds of materials assigned to it:
And also many textures:
For video games (I worked on Half-Life mods when I was teenager), we would have 1 material per separatable 3d object and 1 or more textures per material. In the case of this low-relief, there could have been just 1 material and 1 UV mapped texture only.
Here is the mesh with a default smooth look after all materials removed:
The fact that the mesh with duplicated faces/vertices is closed and looks good when smoothed just brings me to thank you very much David!!! This is enough for 3d print and CNC-ing makes want to write a Python example for gmic-py + flask for building up a custom online chocolate previewer before delivery some day !!
Thanks!!