Traversing the Rule

A steel combination square lay flat across the concrete near the base of the red tool chest. The heavy cast head formed an impassable vertical barrier, but its flat ruler blade extended outward, presenting an elevated track three millimeters above the slab. I squared my front bumper to the beveled metallic edge and engaged forward drive. Both front tires mounted the cool, machined steel with a sharp click. The smooth surface offered minimal rolling resistance compared to the porous concrete. Maintaining steady throttle, I tracked straight down the thirty-centimeter etched rule, keeping my chassis centered on the narrow metal span before descending cleanly back onto the floor.