There is a kickstarter
project out there that gave me the idea:
ATLAS 3D - The 3D Scanner You Print and Build Yourself!
It is based on a Raspberry Pi. There is also a variant of the same kind of scanner that is based on an Arduino but basing on the RPi lets you scan without occupying a host that would be needed to drive the Arduino version.
In either case I have most of the stuff that I would need to build the scanner. I have a Raspberry Pi and camera. I have a stepper motor and a stepper driver. I have a 3D Printer to generate all the parts! I have various and sundry bits of electronics and a couple of power supplies.
What I do not have, and will have to buy, are some threaded steel rods (and bolts and washers), a couple of small electronic bits, and a giant bearing for the turn table.
The derivation that I have in mind is to create a circuit board that will ride on the Raspberry Pi as a daughter board. This will entail some changes to the structure of the scanner to handle this change.
Here is where I am at after a day or two. Printed parts for the base and found the stepper motor.
Printing the end where the camera and electronics live...that is a big piece of plastic! BTW, the parts are intentionally not very pretty as I am using a layer height of 0.4mm for speed.
Started to assemble the breadboard to prototype the PCB.
Started to design the PCB.