A good photo can really go a long way. Back up and zoom in as much as possible to reduce perspective distortion. Try to get the camera square to the part.

Another nice trick for small parts with a flat face is a flatbed document scanner. Unlike a camera, the scanner ensures no perspective distortion. They also have a known scale (the DPI). Or, for more accuracy, you could calibrate the scale factor by scanning a ruler.

If you like OpenSCAD, you should definitely give CadQuery a try. I’ve used both, and CadQuery absolutely blows OpenSCAD out of the water.

What does the probed mesh look like? If you run multiple probe cycles, are the results consistent?