Cubi 25

Cubi 25 is another brilliantly challenging creation from designer Frédéric Boucher, crafted by Pelikan in a striking combination of Mahogany and boldly striped Zebrano. Compact at 65 × 65 × 63 mm, this puzzle may look approachable—but it’s widely considered the most difficult of the four Cubi designs.

Inside the box, several intricately shaped wooden pieces must be assembled into a perfect cube. But the interior isn’t empty: half‑voxel blocks are fixed to the walls, restricting movement and becoming part of the final structure. To raise the difficulty even further, many of the loose pieces themselves include half‑voxel extensions, creating unusual geometries that make even the initial cube assembly a serious test of spatial reasoning.

With only 25 loose voxels plus the two fixed halves, there’s almost no room to spare. Finding a valid cube shape outside the box is already a demanding task—similar to a Soma cube, but significantly more constrained. Once you discover the correct configuration, the real fun begins: inserting the pieces requires rotations, sliding maneuvers, and precise sequencing to navigate the limited entry.

Beautifully made and deeply satisfying, this Cubi edition offers a rewarding challenge for experienced puzzlers and a standout display piece for any collection.