this small ruler can be used as scale reference while taking pictures of your archaeological find - erm - your latest thingiverse design ;-)

based on this 2d-print photographic reference scale by Jim Elder

features:

• overall size is 10x2cm
• several centimeter squares and millimeter ruler for reference
• a 2cm diameter ring for perspective correction
• a gray area for color correction
• mounting holes (for your keyring, backpack, ...)

i printed this with a 0.4mm nozzle, 0.2mm layer-height and 0.3mm extrusion width (which is rather experimental) to get the fine detail for the millimeter tick-marks

prints wonderfully as pseudo dual-color print: print the bottom layers in black, pause, hotswap to white and continue with the top layers (markings/squares/...) :-)

alternatively print the whole thing in white and paint it black/gray

a piece of duct-tape also works quite well as gray color reference area (might be a bit glossy though)