Palm Datum
A small Wavefront OBJ tactile relief object: a chamfered slab, one spine, uneven ribs, three low pins, and a small orientation tooth near the home corner.
Handling
Treat the long raised line as the center spine. The three low pins sit along one edge so the object can be read without looking down. The taller middle rib is the place where the thumb knows it has crossed the center, not a marker in a larger system.
The chamfered corner should point away from the palm. The little tooth near the near corner tells the hand which way the object is facing before the ribs are read.
Dimensions
Unitsmillimeters
Footprint72 mm by 36 mm
Base height3.2 mm
Highest relief5.3 mm
Suggested print0.16 mm to 0.2 mm layer height, no support