Mechanical Digitizers
Table of contents
Atomic Force Microscopy
Atomic Force Microscopy(AFM) or Scanning Probe Microscopy(SPM)
~ nanometer
Image modes
Contact mode, Tapping mode, Non-contact mode
Non-contact Mode: Oscillates above the adsorbed fluid layer on the surface during scanning
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References
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AFM Probe
AFM Probe USC-F0.3-k0.3-10, image above, $980 per 10, Budgetsensors Fabrication steps of AFM Probes
Tip wear and tip breakage in high-speed atomic force microscopes
Touch Probes
Detecting contact by measuring resistance between the balls and rollers.
BLUM, The trigger signal is generated via shading of a miniature light barrier
Bridge Coordinate Measuring Machines (CMM) 
CNC Machine -> Workspace alignment/present setting / workpiece measurement, digitizing or inspection
Optical Optically tracked touch probes GOM
Digitizer Arms
Passive Robot Arm
Typically, robotic arms used in manufacturing offer working volumes ranging from 4 to 12 feet, with radial reach extending from 2 to 6 feet. These arms predominantly come in six- or seven-axis configurations, depending on the specific requirements. Fixed Coordinate Measuring Machines (CMMs) excel in providing extreme precision, surpassing that of portable CMM arms.
DIY
Universal Robots 
You can approximate the functionality of a digitizer arm using any robot arm, by reading the axis rotations and reconstructing the location of the end effector in 3D space. Typically, read-outs from a robot arm will be in Euler Angles.
DIY Projects
Large Scale
Beyond inspection in manufacturing contexts, Frank Gehry was the first architect to incorporate mechanical digitizing into the process of form making: 
The technical complexities behind this feat are documented thoroughly in Dennis Shelden’s 2002 MIT Dissertation: Digital Surface Representation and the Constructability of Gehry’s Architecture 
The precursor to MIT’s Stata Center, Gehry’s 2000 Museum of Pop Culture in Seattle was the first to test translating this digitization workflow into full scale construction:
Digital Templating
Wire based templating devices take measurements from rotary encoders
Survey Prisms
A survey prism is a glass reflector that is used in surveying and engineering to reflect the Electronic Distance Measurement (EDM) beam of a total station.
Site conditions usually vary so greatly that the global coordinate system is not relevant, rather the local coordinate system between particular elements.
Small Robots and Big Projects, Maria Yablonina and James Coleman, ACADIA 2021