A computer-readable medium configured to store instructions for marking one or more items by an object marking system having a conveyor assembly, a laser etching unit, a laser distance sensor, an inductive proximity sensor, and a controller, the instructions comprising delivering, via the conveyor assembly, a container having the one or more items stored therein, the conveyor assembly having a conveyor line and a conveyor drive, the conveyor line including a first portion and a second portion, the second portion defining a marking position of the one or more items; receiving the container on the second portion of the conveyor line; detecting, via the laser distance sensor, the one or more items by measuring a distance from and differentiating between a low surface and a high surface.