Carpal Bloom 04

A guard you wear on your forearm. It starts flat — twelve pointed shields lying over each other like a closed bud — and opens into a wide fan around the wrist. You cut it from one A2 sheet at full size, out of thick card or 1.2 mm felt made from recycled bottles.

Fourteen panels in all. Twelve are the petals. The last two are the cuff bands that wrap your arm and hold every petal at its root. Nothing is glued and there is no hardware anywhere on it — the tabs and the folds do all the work.

The drawing calls it a Phyllotaxis Deployable Forearm Bracer, which is three hard words for a simple thing. Phyllotaxis is the pattern leaves make as they go up a stem. Deployable means it packs flat and opens. So: an arm guard, packed the way a plant packs itself, that opens.

SHEET

A2 · 594 × 420 mm · 1:1, millimetres · ±0.2 mm

PANELS

14 · 12 petals + 2 cuff bands

PETAL

180.0 × 35.0 mm, pointed at both ends

TURN

137.5° from one petal to the next

CUFFS

180 mm long · PANEL 13 inner, PANEL 14 outer

JOINS

12 tabs into 12 slots · 6 slots per cuff

LOCK

T-lock · 12.0 mm tab into a 12.4 mm slot, 12.5 mm deep

MATERIAL

250–300 gsm card, or 1.2 mm recycled-PET felt

HARDWARE

none · no glue required

This is the good part, and it is the reason the bracer opens evenly instead of bunching up on one side.

Almost any simpler number falls apart. Turn 120 degrees and the fourth petal lands exactly on the first: you get three thick stacks and nine bare gaps. 137.5 never comes back round onto a petal already there, so twelve petals means twelve evenly spread petals — and even overlap all the way round is what lets the whole thing close flat and open smoothly.

AN AFTERNOON. LONGER IF YOU CUT IT BY HAND.

1. Print the template at true scale

   The sheet is drawn 1:1 in millimetres on A2, 594 × 420 mm, to a tolerance of 0.2 mm. Print it at 100% / “Actual size”. No home printer takes A2, so tile it across A4 or Letter and trim the overlap — every consumer print dialogue can do this, and the tiles line up because the drawing is dimensioned, not fitted.

   “Fit to page” is the one setting that ruins this. It shrinks the sheet by a few percent, which is invisible on paper and fatal in the tabs: at 97% a 12.0 mm tab is 11.6 mm, and every one of the twelve joints is loose.

2. Check the ruler before you cut anything

   There is a 10 cm ruler printed on the sheet for exactly this moment. Put a real ruler on it. It must measure 100 mm. If it does not, the print scale is wrong — change the setting and print again. Thirty seconds against a whole sheet of material and an afternoon.

3. Cut every solid black line through

   Solid black is a cut. Take the blade all the way through, one panel at a time, and keep the offcuts until the dry-fit is done — a mis-cut tab can be patched from a scrap of the same sheet.

4. Score the red dashed midribs and fold them

   Every petal has a red dashed line down its middle. That is a fold, not a cut. Score it about halfway through on one face only, then fold it flat, a full 180°, so the two halves of the petal touch. Open it again. A scored fold is crisp and stays where you put it; an unscored one bulges and fights the tabs for the rest of the build.

   These midribs are living hinges: the fold is also the joint. There is no pin and no pivot — the material simply bends in the same place every time, and that is the whole reason this thing blooms.

5. Keep the grain arrows pointing the same way

   The arrows are grain direction, and they are on the panels because material has a direction whether or not the drawing admits it. Card folds cleanly along the grain and cracks across it; felt has a roll direction that wants to curl back. Lay every panel on the sheet with its arrow the same way before you cut. On the cuff bands the arrow runs the way the band wraps your arm.

6. Match the circled numbers, edge to edge

   Each edge carries a circled number. Match each number to the same number on the panel beside it, and work clockwise. The full sheet is what carries the run of numbers — the drawing on the card is reduced, and its numbers repeat.

7. Seat the twelve tabs, working clockwise

   Slide each 12.0 mm tab into its 12.4 mm slot — six slots on the inner cuff, six on the outer. Go clockwise and do not skip about: each petal lies over the one before it, so a bracer assembled out of order has a tab you can no longer reach. Work with your fingers, not a mallet. If a tab will not seat, the midrib above it is not folded all the way.

   A 12.0 mm tab into a 12.4 mm slot is 0.4 mm of clearance, and that is the whole fit: tight enough to hold by friction, loose enough to seat by hand.

8. Dry-fit the whole thing — and never glue a hinge

   It holds dry. That is the design, and the dry-fit is where you find out a petal is mirrored, while that is still free to fix. If you want it permanent afterwards, put adhesive on the tabs only. PVA on card, contact cement on felt.

   Never put adhesive on a red dashed line. Glue turns a living hinge into a stiff crease, and the bracer never opens again.

FOUR MARKS, AND THEY MEAN DIFFERENT THINGS

The swatches are drawn on paper because that is where you will meet them — on your own printout, in the sheet’s own black and red.

The design — the petal geometry, the sheet, the card art — is CC BY-NC 4.0. Cut it, remix it, print it for yourself, teach a class with it, put it on a stage: credit it, and do not sell it. The code in the vibe-cards repository is MIT and is not affected by this; two different things, two different grants, and the page that hands you the file is the right place to say so.

vc1|CARPAL-BLOOM-004|Carpal Bloom 04|2026-08|CC-BY-NC-4.0|vibe-cards

The chip carries that line in plaintext, next to the address. It needs no server and no network to say what this card is — so if this page ever dies, the card still knows.

This card printed two numbers for itself for a while — 03 in large type, and an ID line ending 002, which is card 002’s number. Any card printed before 2026-08-16 carries that. Both now read 004, and this is card 004.

This card’s address can never change, so anything new about it has to land here: corrections, a fold order that turned out better, a material someone tried that worked. Tap the card again in a month and there should be something on this page that is not on it today.