iDangle is a ceiling-mounted phone holder designed for watching videos while lying down. Flip a switch to bring the holder down, attach a phone magnetically, then remove the phone and send the holder back up when finished.

Inventor Matty Benedetto presents it as part of his Unnecessary Inventions collection.

Inventor Kazuya Shibata built the Portable Ice Keeper, a freezer designed specifically to transport a single ice cream without melting it. He presents the creation as part of his series of barely useful inventions.

Carlos Reyes built a functional version of Homer Simpson's electric hammer. The 3D-printed prototype moves the hammer back and forth automatically, after design refinements addressing friction, alignment and strength.

The Snack Safe is a lockable container for treats that won't open until you've walked a set distance. To get to the food inside, you first have to earn access by walking.

Matty Benedetto of Unnecessary Inventions built the device around a pedometer-controlled locking mechanism and introduced it on his invention website.

A motor-free, semi-automatic playing-card launcher fires one card each time its trigger is pulled. It uses a suction cup of the kind found on toy projectiles to pick up a single card at a time.

A catapult-style mechanism launches the cards, which are positioned at a slight angle to help them fly straight. Creator tekelili refined the design through several prototypes and demonstrated a card sticking into a cucumber.

Strange Inventions Lab's Fidget Spinner Synthesizer uses the rotation of a fidget spinner as a musical control. The maker describes it as turning motion into music, with the spinner physically moved as part of the performance.

Five signed units were made as a limited-edition instrument and offered through the maker's product page.