A kumiko panel is a wooden lattice with the geometry of a name. The strips of cedar are notched and slotted into each other without glue or nails, and the small pieces that fill the diamonds and triangles of the lattice are drawn from a fixed vocabulary of motifs: asanoha for hemp leaf, kasane-rindo for layered gentian, yae-zakura for the eight-fold cherry. The vocabulary is the craft. A practitioner spends roughly a decade learning to cut the joints cleanly enough that the lattice holds under its own tension. Only then is he considered qualified to choose which motifs go where on a panel he has been asked to design.

What interests me about kumiko is not the woodwork. It is the structure: a curated grammar with an open composition. There is a closed library of motifs, inherited and named, and an open question (where do they go) that the maker decides. That is a different shape from anything I see in software. The defaults in our world are the two extremes. A CAD tool gives you infinite freedom and produces, in the median user's hands, bad output. A pattern generator gives you a slider and produces output the user did not really compose. Both miss the interesting region, which is exactly where kumiko lives: the vocabulary is closed and the sentence is yours.

A printable translation

The tool at custom.ma-r-s.com/customize/kumiko lets you compose a triangular kumiko-style panel in a browser and download it as a kit of STL inserts plus a placement map. A six-step wizard walks you from frame size to palette to style to generator to refinement to download. The cell is a fixed equilateral triangle of CELL_SIDE_MM = 44.5, height side times root three over two, insert depth eleven millimetres. Frames hold anywhere from 3 to 50 cells on a side; the palette runs one to eight filament colours. You print the inserts flat in the colours you chose, drop them into the matching triangles of a wooden frame, and the panel snaps together.

The forty-four patterns in the library are not generated. They were drawn in SVG, traced from the canonical kumiko motif set (the asa-no-ha family, the kuruma wheel group, the kasane-rindo nesting layers, the sakura petals, and a set of geometric variations that appear repeatedly in Japanese pattern catalogues without a settled name), then emitted as physical STLs at the exact cell dimensions. The customizer never invents a motif. Its job is to decide which insert goes in which triangle, in which colour. The library is the part of the project that took the most time and is invisible from the wizard.

The grammar, in code

Five composition modes ship. traditional tiles one motif uniformly across the panel, splitting into concentric rings if the palette has more than one colour. wandering lays a diagonal band of patterns across the panel, sliced into parallel stripes by palette. minimal drops a single off-centre cluster of one motif into an otherwise empty grid. border draws a frame around an empty centre. center places a feature motif in the middle and a different field motif around it. Each mode is a few dozen lines of geometry that operates in millimetres rather than grid indices, because the triangular lattice alternates point-up and point-down cells and any algorithm that reasons about (column, row) parity instead of real (x, y) position eventually produces a panel where the apex flips on the wrong axis and the result is recognisable, immediately, as wrong.

The wizard's output is reproducible. The seed is a number; the state (cols, rows, palette, style, density, banned patterns) lives in the URL under short keys like c, r, p, st, sd. Hand someone a link and they get the exact panel you designed, regenerable in their browser, downloadable as the same ZIP. The kit is a README.txt manifest, a panel.svg placement map with every triangle labelled <pattern><colour>, and one .stl per unique motif used. The README tells you how many copies of each insert to print, in which colour. A panel of forty filled cells with three motifs and two colours becomes six lines of build instructions.

"This isn't kumiko"

The objection is real. Kumiko in cedar is not a category of decoration. It is a relationship between a material that splits cleanly along its grain, a knife sharpened by hand, a joint geometry that holds because wood compresses against wood, and a body that has cut ten thousand of the same shape until the cut is accurate without measurement. Fused filament fabrication reproduces none of that. A PLA insert in a PLA-printed lattice is not kumiko in any honest sense; calling it kumiko is the kind of borrowing that flattens a craft into a mood.

So the project does not claim to be kumiko. It claims to be a translation of one specific layer of kumiko, the compositional grammar, into a medium where that layer is portable. The grammar separates cleanly from the woodwork because it always was separate. The patterns were named and inherited long before any one practitioner cut his first strip. The composition is what the apprentice earns the right to do at the end of his training, and it is the part that does not require the cedar at all. Borrowing it for fused filament does not pretend to be a master joiner. It pretends to be a different kind of person, with a printer, holding the same small grammar in his hands and choosing where the asanoha goes.

The thing the original craftsman has and I do not is the part that takes a decade. The thing he and I share is the question of where the petals nest. The customizer is the second of those, made portable by the modesty of the first.

Live at custom.ma-r-s.com/customize/kumiko.