This DIY 3D-printed Halloween mechanical surprise box is a cleverly designed interactive toy. Turn the side gear, and the lid pops open in an instant, revealing a cute ghost and a pumpkin head peeking out—one after another—bringing endless fun.

The front of the box features a custom Halloween relief engraving: a soft, adorable ghost cradling a jack-o’-lantern, accented with tiny stars and a crescent moon. Its bold, clean lines are optimized for 3D printing, with no delicate or fragile parts, ensuring a high success rate. The entire piece is printed in two-tone PLA—off-white base paired with orange-and-white contrasting components—while the mechanical gears and snap-fit joints glide smoothly, exuding a distinct handcrafted feel.

All mechanical parts are integrated into a single print, requiring no additional hardware. It makes a charming desk decoration as well as a stress-relieving, interactive toy, perfect for Halloween displays or thoughtful gifts. With its original mechanical design, this piece stands apart from ordinary ready-made ornaments, letting you experience the joy of combining 3D printing with mechanical engineering—and hiding little Halloween surprises inside this delightful box.