I always thought of this idea for use with safes in POH's. You got a spinning roulette wheel attached to your safe: "Click use safe" 1. You click a number. (1-9 and 0) 2. The wheel spins randomly. 3. You click the next number. 4. 4 or 5 number input. But, like you guys said, "what if you forgot the pin?" Only thing I can think of is recovery questions (oh god), or bury the code in a random spot with a spade (lol).