Live event producers build a run-of-show (ROS) in a spreadsheet or doc, then manually re-enter every cue duration into their stage timer software. When the ROS changes during rehearsal, which it always does, they retype durations twice and hope nothing drifts. Stagetimer Run-of-Show Builder is a drag-and-drop ROS editor that treats the show rundown as the source of truth and auto-syncs each cue's duration to Stagetimer displays. Producers reorder segments, adjust a keynote from 20 to 15 minutes, and the timer feed updates instantly with no re-entry. The MVP is a web app: build an ROS with segments, owners, and durations; a live sync bridge that pushes cue timers to Stagetimer via its API or as a companion display; and a shared read-only view for stage managers and speakers. Revenue is a straightforward per-seat or per-event SaaS subscription aimed at corporate AV producers, with a higher team tier for agencies running multiple shows. Go-to-market starts by targeting existing Stagetimer users directly, since they already feel the double-entry pain, plus corporate AV and event-production communities. Growth loops come from the shared ROS view: every speaker and crew member who receives a live rundown link sees the product in action during a high-stakes show, and stage managers carry the tool from client to client across the freelance-heavy event world.