A Lego collector's app has to solve a weird problem: the same product is a toy, an investment, and a market with real price volatility — all at once. On Bricksecret, I mapped that into three systems that don't fight each other: Hot Deals for timing a buy, a searchable Database for finding the exact set, and a Portfolio that tracks purchase price against current market value so a collector can actually see when to sell. The hard part wasn't any single screen — it was building an IA with six user scenarios that could hold speculative investing and casual browsing in the same flow without either one feeling bolted on. We shipped 103 screens and a clickable prototype the client could test before a single line of code got written. What's the trickiest part of designing for users who are part hobbyist, part investor? Check the case study