Thanks, Judy, for that suggestion. I noticed that my new Dell
all-in-one scanner (as much as I like it for printing photos) didn't
do a very good job at making pictures of 3d objects placed on the
glass, compared to my old Astra.
But I have to object to calling what you're doing with these flatbed
2d scanners "3d scanning". That just leads to confusion about a
product most people don't know much about. Real 3d scanners yield 3d
output, not just pictures. They use a laser or touch probe to gather
positional from the surface of a 3d object, so that the
object can be reconstructed in 3d and reproduced with a mill or RP
machine. They tend to be more expensive than 2d scanners, but they
address an entirely different task.