Be great to hear from you, however crazy your guess. We're operating according to the brainstorming ground rules. You can guess more than once as new ideas occur to you, but even if you're right, you won't find out until Saturday. You might want to visit the Clues to get you thinking.
Send it to us at enigmaker@cefn.com including the word #project5 somewhere
Make a guess through Twitter by including @enigmaker and #project5 in your tweet, e.g.
@enigmaker #project5 is a combination knock system, the led shows the number of knocks, the headphones tell you which figure of your PIN
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