Write a comprehensive Monte Carlo simulation model specification for {{industry}} in a {{tone}} tone for {{target_audience}} at a {{complexity_level}} level. The goal is a step-by-step guide to build the model in Excel or Google Sheets. Output as numbered steps with action title, instructions, expected outcome, and common pitfalls. Cover: Model Overview, Input Assumptions, Model Structure (3 tabs), Scenario Analysis (Base, Bull, Bear, Breakeven), Sensitivity Analysis (2-variable tables), Quality Checks. Maximum 1600 words. Every recommendation must be specific to {{industry}} and {{target_audience}}. If a formula cannot be determined with high confidence, skip that section. Paste any relevant background information after these instructions before running.