Snap Lines: Use a chalk line or laser level to mark the path on the ceiling or wall. Mark Support Points: Mark the spots where supports will be installed. Standard intervals are usually every 1. Measuring and marking: Accurate measurement and marking techniques for cable trays. Calculate horizontal, vertical, or compound cable tray offsets based on bend angle, offset distance, and available installation. Watch how a professional fabricator perfectly marks, measures, and cuts a cable tray using a hand grinder with complete accuracy. I have used a marker with a speed square on projects, but that is a rough method.