At first glance this puzzle looks completely impossible — a solid structure with a ring that appears permanently trapped inside,but the secret is surprisingly simple. A hidden magnet pulls the inner rod to one side, allowing the ring to slide out once you make the right move.

The fun comes from how unexpectedly easy the solution is once discovered.

This puzzle is easy to print, easy to assemble, and makes a great desk toy.

Printing & Hardware

This model is almost fully 3D printed. The only required hardware is:

• 1× Ø12 × 2 mm neodymium magnet

• Dowel pins:  1. 3× Ø5 × 50 mm

                         2.1× Ø5 × 40 mm (must be steel)

You can get the pins from Maker's Supply, but note:

•      The outer 3 pins for the cage (50mm) from MakerLab are fine            
• The inner pin (40mm) must be steel. (Maker's Supply pins are stainless steel and will not be attracted by the magnet)

Magnet embedding step

• The housing is designed for a pause-at-layer magnet insert
• When the print pauses, add a small amount of superglue to the magnet pocket
• Insert the Ø12 × 2 mm magnet, then resume the print
• ⚠️ Do not skip the glue!. There is a clearance fit between the magnet and the pocket and because of that  the magnet can stick to the nozzle and ruin the print.

Assembly Instructions

1. Print all parts
2. (Optional but recommended) Lightly sand the ends of the three outer pins so glue adheres better
3. Apply glue to the pin holes in the bottom housing (the half without the magnet)
4. Press the three outer pins into place
5. Insert the steel inner pin and the ring
6. Apply glue to the pin holes in the housing with the magnet

7. Align the holes in the housing with the magnet with the pins and press the it into place