super simple cookie cutter generator

Foreword:
OpenSCAD is a powerful freeware to create technical objects.
The "cookie cutter" project uses the "surface" function, which creates a 3-dimensional object from a 2-dimensional PNG image.
The height of the pixels is calculated from the grayscale value.
That takes a lot of computing power.
Therefore, you should not use too large a resolution if you have a weak computer.

Step 1 -the picture-
You take your picture and cut away the unnecessary border.
Then you color the outline black and the background white.
The details in the middle are light to dark gray depending on the height.
Then you convert it to a grayscale PNG image with a low resolution.
recommendation: about 300x300 pixel or less
You save the image as "cutter.png" in the same folder as the OpenSCAD file.
(I like GIMP)

Step 2 -OpenSCAD-
You open the OpenSCAD file with a new version of OpenSCAD.
Now please enter the final height and width of the cookie cutter.
You have to enter the size of