Ultra-difficult puzzle

A 15-piece puzzle with a gap of only 0.002mm, polished to the utmost limit.

Experience the “Taste the Difficulty” for adults.

Try this 15-piece puzzle of extreme difficulty that a Japanese manufacturing company has seriously pursued for fun.

Experience the challenge

It's not easy to solve. I'm not including the answer on purpose.

It's hard to tell which side is which because it's mirror-finished on both sides.

It's so well-designed that all the pieces look the same, so even if you get a piece that fits for a bit, it won't work in the long run if it's not the right one.

There's only one answer.

ZIREL's world, made possible by gaps narrower than a single strand of hair.

Iwai Press Co., Ltd. (located in Otsuki City, Yamanashi Prefecture) specializes in technology for filling gaps.

Experience gaps as small as 0.002 mm, invisible to the naked eye, through ZIREL.

PRODUCTION PROCESS

Zirel cannot be mass-produced.
Each puzzle is a one-of-a-kind item that takes time and effort to produce piece by piece only after an order is made.


It requires about 10 processes over 72 hours to complete.
Iwai Press brings together several techniques to meticulously craft it.

Creating a Design

Our designers create a rough outline

Drafting

The design is then drafted into CAD data

Flattening of Metal Surfaces

Warping and other distortions of the quenched industrial stainless steel are flattened and hardened in a polisher

Pieces Cut with a Wire EDM

When the stainless steel is ready for processing, its pieces are cut using a brass wire with a thickness of 0.2mm in water.
(Processing time for one puzzle is about 10 hours)

Profile Polishing

After the cutting, each piece can have burrs about 0.05mm in size. So they are further polished while a craftsperson inspects its profile by eye

blast polishing

After the profiles are polished, metal powder is removed and the pieces are further polished by blasting them with diamond particles

All Pieces are Assembled

Final Polishing on a Precision Grinding Machine
After assembling the pieces, the final polishing is performed on a precision grinding machine and with our craftsmanship until the spaces between the pieces become invisible

Buffing for a Mirrored Finish

After the final polishing, buffing is done to give it a mirrored finish and glossy look that is the real appeal of Zirel