PRINT METHODOLOGY AND REFERENCES - Acetaminophen (CAS 103-90-2) - ANT HOUSE 2026-10-30 (procedure v7)

1. WHAT THIS MODEL IS
  A one-piece ball-and-stick model for material-extrusion (FDM/FFF) printing.
  Atom positions and bond geometry come unchanged from the molecular structure
  record; the design never moves or deforms the molecule (checked on every
  build: every source point within 0.001 mm of the printed surface outside the
  pencil and cup zones) [Z]. Everything added for printing - base, pencils,
  cups, raised logo - is a separate solid joined to the molecule.
  Element symbols are engraved on the spheres facing the viewer.

2. DESIGN DECISIONS AND WHY
  a) Vertical pencils only. 13 hexagonal posts stand straight up from the
     base under atoms that have a free vertical path. Diameter grows with length
     (3.5 mm and 5.0 mm) so no pencil is slender enough for the slicer to flag it as a
     "thin fragile part" [Z]. Tilted posts were rejected (design decision).
  b) 45-degree cups. A neck under a sphere supports only a small cap of it:
     a neck of radius r under a sphere of radius R reaches asin(r/R) from the pole
     (10-21 degrees here). Each pencil therefore ends in a cone at 45 degrees,
     tangent to the sphere and cut at 50 degrees, so the lower sphere surface is
     never steeper than the self-supporting limit of about 45 degrees [R 1][P 11][Z].
  c) Slicer supports for the rest. Spheres without a free vertical path are
     supported by the slicer's organic (tree) supports [M 8]. Settings keep every
     tree on the base, never on the bed beside it (molecule fitted inside a
     circle of radius 44 mm over the flat top, branch angle at most 25 degrees,
     bridges not supported) [Z].
  d) Molecule centred on its minimum enclosing circle (Shapely), which allows
     the largest scale that still fits the base: 10.14 mm per angstrom [Z].
  e) Raised MolGod logo across the top of the base: symbol 1.4 mm, lettering
     1.0 mm, 45-degree bevel on every edge so it needs no support [R 1][Z];
     thinnest lettering stroke 1.42 mm (nozzle 0.4 mm).
  f) Base lettering on the vertical front face has a 45-degree chamfer (no flat
     ceiling that would need support) [R 1][Z].
  g) Profile for the thin upper part (cooling, minimum layer time, z-hop,
     acceleration): PRINT_INSTRUCTIONS.txt section 4. Interlayer bond strength
     in extruded polymers depends on the temperature history of the layers
     [R 4][R 5]; the specific values are practitioner recommendations
     [M 6][P 15][P 16] and HYPOTHESES until confirmed by our test prints.

3. HOW WE VERIFIED THIS FILE (before any physical print)  [Z]
  Slicer: PrusaSlicer 2.8.1 (command line), profile slicer_profile.ini.
  B0 heating   bed >= 50 C and nozzle >= 190 C before the first layer ...... PASS
  B1 stability slicer reports no floating or thin fragile part ............. PASS
  B2 mid-air   G-code analysed layer by layer (0.1 mm raster): extrusion in
               the molecule with nothing underneath .......................... PASS (molecule 0, base 0)
  B3 on base   slicer support moves outside the round base ................. PASS (sides/back 0, front 0)
  B4 logo      raised logo present in the G-code ........................... PASS
  Geometry     molecule untouched, one watertight solid, base dimensions,
               engraving depth, QR code, author mark ....................... PASS
  Each instrument is checked both ways before it is trusted (e.g. a cube must
  pass B1 and a floating sphere must fail it; the same model without supports
  must show mid-air regions in B2).

4. WHAT WE DO NOT KNOW YET
  - No physical test print of this release has been reported yet.
  - Peer-reviewed limits for pencil diameter versus height, neck diameter for
    clean cutting and engraving depth on small spheres were not found; the
    values used are our measurements and practitioner reports.
  - Other slicers may treat the 3MF settings differently (PRINT_INSTRUCTIONS 2).

5. COMPARABLE WORK
  Published one-piece ball-and-stick FDM models with built-in supports were not
  found; published approaches split the model into parts [R 22] or print with
  slicer supports [R 21]. See also [R 23].

6. REFERENCES (accessed 2026-10-21; DOIs verified in Crossref)
  Peer-reviewed [R]
  [R 1] Jiang J., Xu X., Stringer J. (2018). Support Structures for Additive
        Manufacturing: A Review. Journal of Manufacturing and Materials
        Processing 2(4), 64. https://doi.org/10.3390/jmmp2040064
  [R 4] Seppala J. E., Hoon Han S., Hillgartner K. E., Davis C. S., Migler K. B.
        (2017). Weld formation during material extrusion additive manufacturing.
        Soft Matter 13, 6761-6769. https://doi.org/10.1039/c7sm00950j
  [R 5] Kuznetsov V. E., Tavitov A. G., Urzhumtsev O. D. et al. (2019).
        Hardware factors influencing strength of parts obtained by fused
        filament fabrication. Polymers 11(11), 1870.
        https://doi.org/10.3390/polym11111870
  [R 21] Scalfani V. F., Vaid T. P. (2014). Journal of Chemical Education 91,
        1174-1180. https://doi.org/10.1021/ed400887t
  [R 22] Paukstelis P. J. (2018). MolPrint3D. Journal of Chemical Education 95,
        169-172. https://doi.org/10.1021/acs.jchemed.7b00549
  [R 23] Penny M. R. et al. (2017). Journal of Chemical Education 94,
        1265-1271. https://doi.org/10.1021/acs.jchemed.6b00953

  Manufacturer documentation [M]
  [M 6] Prusa Research, Knowledge Base: Cooling.
        https://help.prusa3d.com/en/article/cooling_127569
  [M 7] Prusa Research, Knowledge Base: Stringing.
        https://help.prusa3d.com/article/stringing_1805
  [M 8] Prusa Research, Knowledge Base: Organic supports.
        https://help.prusa3d.com/article/organic-supports_480131

  Practitioner reports [P] (grey literature: opinions, not measurements)
  [P 11] LulzBot forum: Suggestions for printing a small ball shape.
        https://forum.lulzbot.com/t/suggestions-for-printing-a-small-ball-shape/3948
  [P 12] Prusa forum: Round base won't print right.
        https://forum.prusa3d.com/forum/how-do-i-print-this-printing-help/round-base-wont-print-right-photos-settings-3mf
  [P 13] Printables: Pin Support Sphere Challenge (comments).
        https://www.printables.com/model/310666
  [P 14] Dreaming3D: Design your own supports in CAD.
        https://dreaming3d.net/blogs/news/stop-fighting-your-slicer-design-your-own-supports-in-cad
  [P 15] Printables: Pin Torture Test (comments).
        https://www.printables.com/model/490899
  [P 16] Bambu Lab forum: How to fix layer wobble for tall and skinny parts.
        https://forum.bambulab.com/t/how-to-fix-layer-wobble-for-tall-and-skinny-parts/56301
  [P 17] Printables: DNA helix (comments on z-hop).
        https://www.printables.com/model/29825
  [P 18] Prusa forum: Bed flinger - slower Y movement as a function of Z.
        https://forum.prusa3d.com/forum/prusaslicer/bed-flinger-slower-y-movement-as-function-of-z
  [P 19] Prusa forum: Issue with debossed text.
        https://forum.prusa3d.com/forum/english-forum-original-prusa-i3-mk4s-how-do-i-print-this/issue-with-debossed-text
  [P 20] MyMiniFactory: 3D print caffeine necklace (hydrogen atoms broke off
        with the supports).
        https://www.myminifactory.com/object/3d-print-caffeine-necklace-43955

  [Z] MolGod.org own measurements for this release (build report and slicer
      analysis included in this package).
