Queue sensor with ESP32 and HC-SR04

This box, rack, lid, and sensor mount form a system for monitoring queue length with five ultrasound sensors. The code for the devices is to be found in my Github account:

https://github.com/HeikkiHietala/queue_sensor

See http://www.sabulo.com/sb/3d-printing-2/low-cost-low-impact-queue-monitoring-system/ for what this does, and also on Instagram as @isohoo3d.