Those instant hand warmers that heat up after a simple chemical reaction can be a lifesaver when you find yourself stuck outside in the cold for extended periods. But even the single-use disposable ones can cost $3 to $5 each. Instructables user junits15 posted a way to make your own in minutes with materials you probably already have at home.

The DIY instant hand warmer starts off with a large zipper plastic bag filled with a small amount of calcium chloride pellets. These are also known as ice melter pellets and can be found in most hardware stores in the colder months. Then fill a snack-size plastic zipper bag with water and put it inside the larger bag.

When the larger bag is sealed, you drop the whole assembly into a pocket or bag and wait for your hands to freeze. Then just pull it out and squeeze until the water comes out of the smaller bag and comes into contact with the calcium chloride pellets. The resulting chemical reaction warms up the bag and keeps it warm for 20 minutes to an hour. Get the full instructions here on Instructables.

The post Make a DIY Hand Warmer With Household Items in 5 Mins first appeared on Gajitz.

The right Halloween decor can make or break your whole holiday, and Instructables user TheNewHobbyist has created the pitch perfect Halloween display. Using styrofoam heads, and Arduino UNO, a karaoke machine, projector, and a few other bits and bobs, the creative tinkerer built a quartet of singing busts for the Halloween porch.

TheNewHobbyist modeled the project after the crowd-pleasing Haunted Mansion ride at Disneyland/Disneyworld. The display consists of four heads that sit on a table and sing a spooky song when the display is tripped by an industrial photocell switch. The projected images came from a YouTube video of four singing heads that, when projected to line up perfectly with the styrofoam heads, seem to create life-like decapitated minstrels.

In the Instructables explanation, TheNewHobbyist explains that having a mechanical engineer as a father was a big help in creating the creepy display. The effect is surprisingly realistic; the projected faces and recorded music really make the faces look like they’re singing and are sure to freak out all of the unsuspecting trick-or-treaters who come by looking for candy. Hop on over to Instructables for the technical specs and instructions to make your very own haunted Halloween display.

The post Spooky, Scary Sight: Decapitated Singing Halloween Heads first appeared on Gajitz.

We used to take Tetris everywhere with us on our Gameboys, but this is the 21st century and we’re all about constant, unfettered access to fun. Never mind all of the other portable consoles, smartphone games and everything else we use to amuse ourselves – Marc Kerger has invented a wearable game of Tetris.

The Tetris T-shirt features a screen with 128 LEDs; behind the scenes are two Adafruit Matrix controllers and four 3D printed soft button controllers. An Arduino controller and the battery compartment are housed in 3D printed covers to keep them protected from your sweat. The battery compartment is removable and presumably (hopefully) the T-shirt is washable.

Although the shirt doesn’t play the iconic Tetris music, the gameplay is surprisingly fun and easy looking…but you’ll have to learn to play upside down. Offering to let someone else play the game on your shirt  might just be a great way to make a new friend, though. Kerger’s shirt is a one-off personal creation that he doesn’t plan on selling because of its high cost, but you can get the programming instructions from his own info source: the Pumpktris on Instructables.

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Humans are perpetually worried about robots one day taking over their jobs, but we never thought tattoo artists were in danger. French designers Appropriate Audiences made a custom attachment for a MakerBot 3D printer that turned it into a mechanical tattoo artist.

The group first used the MakerBot to create the attachment that would allow the 3D printer to perform a new trick. They installed, tweaked, and tested the automated tattoo machine. They experimented with skin tension and other variables to be sure that, when the contraption was tried out on a human, it wouldn’t horribly maim or dismember that human.

When the team worked out all of the details, a very brave member of the group stuck his arm into the machine and allowed the modified tattoo gun to permanently imprint his skin. The tattoo was just a simple circle, no doubt due to the newness and untested nature of the contraption. In the future, though, we can definitely imagine more complex tattoos being drawn by machines.

The post Evil Geniuses Turn 3D Printer Into Robotic Tattoo Machine first appeared on Gajitz.

Remember playing with a Magic 8 Ball when you were a kid? You would ask a ‘yes or no’ question, then turn the ball over to see its highly dependable answer floating up through a mysterious blue liquid. It was fun, but there were only 20 possible answers and it got old pretty quickly. DIY-er Jason Poel Smith decided that the toy deserved a 21st century upgrade.

Smith met his goal by cutting apart a Magic 8 Ball, scooping out its innards and replacing them with a small digital picture frame. The frame can hold up to 60 pictures at a time, and what those pictures are is up to the user. You can change them at any time through the handy new USB port created during the project.

The project looks easy enough, but it would be kind of a pain to work with all of those little pieces and avoid super-gluing yourself to all of them. If you’ve got more patience than we do, you might have some fun making this digital magic 8-ball and loading up some crazy pictures on the tiny screen. The only drawback seems to be that the digital frame doesn’t have an accelerometer to tell it what position it is in, so it can’t be activated by just flipping the ball over. It will cycle through all of your pictures as a slideshow, and whatever pic happens to be on the screen when you flip the ball over is your answer.

The post 21st Century Magic 8 Ball Lets You Set Customized Answers first appeared on Gajitz.