SHUKUSHAKU / REUSABLE PLA SET
Contents: 4 ArUco tiles (labelled 1-4; encoded IDs remain 0-3), 1 dual-use QR, slim tray and lid.
Units: millimetres. Print at 100%, matte white + matte black PLA.

TILES: 60 x 60 x 0.8 mm, black reference 45 x 45 mm.
QR: 60 x 60 x 0.8 mm, 45 mm symbol. Opens website and measures scale.
0.8 mm is the selected thin reusable design, not a universal printer minimum.
The thin tiles remain flexible; discard or reprint warped tiles.

SINGLE EXTRUDER: print each *combined.stl flat. 0.2 mm layers including first
layer, solid infill; white for 3 layers (0.6 mm), black for the last (0.2 mm).
Set the filament change BEFORE the first black layer at 0.6 mm.
MULTICOLOUR: use the white base plus corresponding black STL as parts of ONE
object. Preserve original positions. Do not drop black parts onto the bed.
Print the common ArUco white base FOUR times, one with each unique black ID.
Do not also print combined versions when using the separate colour parts.
File aruco-0 = Tile 1, aruco-1 = Tile 2, aruco-2 = Tile 3, aruco-3 = Tile 4.
Paper labels are 1-4 at bottom centre. Keep marks outside the black pattern.

CASE: tray 63 x 63 x 5.2 mm; lid 66 x 66 x 2.2 mm.
Closed envelope: 66 x 66 x 5.8 mm. Floor/roof 0.6 mm, walls 1.2 mm.
Stack the four tiles face up, then the QR on top; use clean paper
interleaves if desired (up to 0.6 mm total spare height). Push from underneath
to remove the stack. The 60.6 mm cavity gives 0.3 mm clearance per side.
Lid interior 63.6 mm gives 0.3 mm clearance around the tray. It is a lift-off
cover, NOT a snap lock. Use a small elastic band to retain it during transport.
Print tray floor down and lid flat outer face down/open side up. No supports.
0.4 mm nozzle, 0.2 mm layers; solid floors/roof. Preview all walls in slicer.
Fit depends on shrinkage, first-layer expansion and printer calibration.
Prototype: digitally checked, NOT physically printed or fit-tested.
Adjust case clearance if needed; NEVER scale the marker STLs for case fit.

SCANNING: remove tiles from the case and place around the document.
All black faces must be level with the drawing. Raise the drawing by the
MEASURED tile height (nominally 0.8 mm), or recess the tiles. Do not scan in tray.
Measure every black square and enter its actual size in the app if needed.
Use 2 or more unique IDs; all 4 provide more references if fully visible.
Test decode, flatness and a known dimension in BOTH axes before relying on output.
Avoid heat/sunlight in storage: thin PLA may warp.

PAPER & CAMERA CALIBRATION: shukushaku-print-pack.pdf is US Letter.
Use shukushaku-print-pack-a4.pdf for A4. Print at Actual size / 100%.
For simple scans use QR alone; for small QR images, oblique views or a large
document, prefer 2+ ArUco tiles around the boundary. All must be coplanar.
The ChArUco board is intentionally printed on paper and mounted rigidly flat.
Known-size scanning needs no markers. Optional old QR measuring mode remains.
https://scale.3dmylogo.com/
Design guidance: https://help.prusa3d.com/article/modeling-with-3d-printing-in-mind_164135
