About the ModelExperience the mesmerizing magic of 3D printing with this impossible passthrough fidget toy! Watch as the inner star-shaped core seamlessly spirals through the outer hourglass shell, creating a highly satisfying, smooth mechanical illusion.Perfect as an anti-stress desk toy, a conversation starter, or a showcase piece for your 3D printing capabilities.

Designed with perfect symmetrical proportions: 80 mm in height and 50 mm in diameter at both the top and bottom bases, making it incredibly comfortable to hold and flip in your hands.Premium feel & smart design: The model features 0.5 mm fillets on the main edges for a smooth, tactile grip, along with highly functional 1 mm chamfers at both the top and bottom openings to ensure effortless insertion of the inner piece.

Engineering Tips for a Perfect Print:

Perfect Tolerances: The model is engineered with a precise 0.2 mm clearance between the inner and outer parts. Ensure your printer is well-calibrated for dimensional accuracy to achieve that buttery-smooth sliding action.

Elephant Foot Prevention & Easy Assembly: The 1 mm chamfers at the top and bottom aren't just for looks—they act as a perfect guide for inserting the inner piece and completely counter any elephant foot expansion on the first layer. Your parts will fit together perfectly right off the build plate!

Z-Seam Alignment: For the smoothest rotation, set your Z-seam to Random or carefully align it to the sharp inner corners of the star profile. A thick, protruding Z-seam line might catch and prevent the two parts from sliding easily.

Print SettingsThis model is highly optimized for flawless FDM printing and a satisfying mechanical fit.

Material: PLA, PETG, or Silk PLA (Dual-color or Silk filaments look absolutely stunning with the curved spiral reflections of the hourglass shape!).

Orientation: Print both pieces separately, standing vertically flat on their 50 mm bases.

Supports: Absolutely no supports! The overhang angles are perfectly designed to print cleanly as is.

Infill: 10-15% (Gyroid or Cubic).

Perimeters/Walls: 2 to 3 walls for structural rigidity.

Explore My Profile!If you like this design, check out my profile for more high-quality 3D-printable accessories and educational toys! Don't miss my Professional TIG Welding Torch WP26 Style Engineering Accuracy . Your support helps me continue creating professional-grade, engineered models for the community!