Lego NXT - THE ULTIMATE SAFE
Check http://www.bouwvoorbeelden.nl/home_eng.htm for more instructions. The display shows 5 small locks... When you turn the dial AND change direction, the Safe "accepts" the code that was on the display just before you changed direction... One small lock (in the display) opens to confirm the code entry. After doing this five times you wait... It starts laughing when you took a wrong combination! So the lock accepts 5 numbers by changing the rotation direction of the wheel. And, dialing 45 to the right is not the same as 45 to the left. So you have 5 entries of "-99to +99". It does not tell you what code is correct.