BBMM
Blind Box Marble Maze
A solid cube with holes on the surface, hiding a tunnel maze inside.
Tilt it and listen for the marble to find its way from one opening to another.
What it is
Every cube is a single, continuous tunnel network 3D printed straight through a solid block; no window, no removable panel, nothing to see inside.
You solve it by feel: tilt, listen for the roll, notice when it stops (a dead end) or drops out a different opening than you expected (a connector shortcut you didn't know was there), and slowly build a map of the maze in your head.
Get one, ready to print or already printed, here: thangs.com/designer/cunicode/collection/Blind Box Marble Maze
Difficulty modes
NTENSE → 2 holes, one continuous path A single unbroken tunnel between two openings. No branches, no dead ends — just one long path and your own sense of orientation.
IMPOSSIBLE → 2 holes, 2 connectors, 4 dead ends Four blind pockets swallow the marble and send it back. Two connector bridges quietly link parts of the maze that shouldn't be shortcuts. The path that sounds right often isn't.
INSANE → 4 holes, 4 connectors, 6 dead ends Four entry points, six dead ends, four connector tunnels weaving cross-links through the whole network. More than one route through — most of them wrong.
Downloadable STL files for 3D printing,
or order one already printed. See all variants →
How it's made
Each maze is generated by a script:
Build a random spanning tree over a grid of cells, using simulated annealing to hit a target number of surface openings, branch points, and dead ends.
For the harder difficulties, add "connector" bridge tunnels — extra routes woven back into the tree, turning it from a simple branching path into a real graph with shortcuts and false leads.
Sweep the whole tunnel network into a CAD solid with smoothly filleted bends (so a marble never catches on a sharp corner), and boolean-cut it out of a cube.
Before any file ships, verify the result will actually print as one correct, watertight piece — no accidental split pieces, no missed hole — by checking the solid's topology (Euler characteristic) against what the tunnel graph's structure predicts it should be.
