SnipFold

Faceted slit-square pinwheel

One 120 mm square with four diagonal slits: alternate tips return to the axle on two right-angle bends per blade. Display first; an optional free-running mount requires a physical spin test.

Materials

  • One sheet of 90-120 gsm paper; scissors; ruler; blunt scoring tool
  • Adult-operated 2.4 mm hole punch or awl with a protective cutting mat
  • External attachment: headed straight pin / axle about 35 mm long, shaft 0.8-1.0 mm, head wider than 3 mm
  • External internal spacer: drinking-straw sleeve cut to about 15 mm; bore wider than the axle
  • External rear spacer: smooth bead about 3 mm, bore wider than the axle
  • External handle: wooden stick with a firmly attached thick cork axle socket; adhesive for the cork only
  • Display option: removable tape to immobilize the rotor at its rear hub

Finished size: Paper rotor within 120 x 120 x 16.75 mm; external handle and axle not included

Steps

CutValley foldMountain foldGlue area

  1. Print and cut one square

    Print at 100% actual size; measure the 50 mm ruler and 120 mm square. Cut P1 perimeter, then the four solid diagonal slits from each corner only as far as the inner endpoint, 8 mm from each center axis. Keep the central 16 mm square intact.

  2. Punch five holes and score

    An adult punches all five 2.4 mm holes over a protective mat. There is one center hole and one selected tip hole beside each slit. Lightly score all eight dashed valley lines with a blunt tool; do not cut these lines.

  3. Return the first tip

    Keep the printed face upward. Start with the hole at (50,55) mm relative to the square center. Lift its outer blade at the inner dashed line by 90 degrees, then turn the tip inward another 90 degrees at the outer dashed line, with the printed face inside both bends. The short panel stands up and the tip panel lies parallel above the hub; align its hole over the center without pulling.

  4. Stack the other three tips

    Repeat counterclockwise from the first blade, viewed from the printed side. Bring only the punched tips to the center; leave the other four corners out. Place each new tip above the previous one. Follow the slightly different crease spacing on each blade; the four holes should share one axle line about 16-17 mm above the rear center hole.

  5. Fit the external axle

    Adult only: pass the headed pin from the front through all four stacked tip holes, through a roughly 15 mm straw sleeve in the gap, then through the rear center hole and a 3 mm bead. Seat the sharp end fully inside a thick cork secured to the handle. Leave about 0.5-1 mm running play rather than clamping the paper. Adjust sleeve length to the actual gap; no glue in holes or on the axle. The head must retain the tips and the bead must keep the rotor clear of the handle.

  6. Choose display or test rotation

    For a fixed display, tape the rear hub to the mount. For an optional working spinner, omit that tape and check gently by hand that the rotor turns freely without wobbling off, scraping the handle or exposing the pin point. Test with a gentle fan, keeping hands and faces clear; adjust clearance if it binds. Do not claim working status until a real build rotates reliably. Store safely away from small children.

Notes

The 3D model shows each piece in its finished, idealized shape; the exploded view only spreads the pieces apart. It is not a paper-physics simulation: curved shapes are forming guides, not exact physical folding or proof of developability, and intermediate fold shapes are not supplied.