Foldable signs to be put on the lab doors, showing one of the two messages:
1) Keep the door closed (closed position) / Measurement in progress (open position)
2) Authorized personnel only (closed position) / Do not enter (open position)
Holes fit neodymium magnets (diameter = 10mm, thickness = 2mm)
Depending on the printer, XY compensation may be needed.
The author hasn't provided the model origin yet.