Build a ringing or knocking machine
Knock, knock, knock. Ding dong! Create a machine that can let you know when a guest is at the door.
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Mechanical Engineering
Step 1
Knock, knock, knock. Ding dong! Create a machine that can let you know when a guest is at the door.
Final steps
You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!
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