There is a growing concern in the open-source 3-D printing community that broad patent claims on materials for 3-D printing may hamper the open-source 3-D printing community's ability to innovate. Thingiverse published a relatively simple algorithm as a defensive publication of prior art to help identify obvious materials for 3-D printing here: http://www.thingiverse.com/thing:73427 (I'll paste it below)
It appears to me to more or less cover every conceivable 3-D printing (additive manufacturing) material. Is this an effective defensive publication of prior art by the obvious clause? Are all 3-D printing material patents ideas that can be generated by the algorithm void after April 13, 2013 when it was published? What about the ones that came before?
How to use the algorithm:
Variables and definitions: @ = “All of the preceding materials and” & = “All combinations of all possible mol fractions of the above” (e.g.  chemicals a+b, a+c, a+b+c, etc. until all combinations have been reached over the set up to N+M and  all fractions so that compound [ax][b1-x] would be stepped through from x=0 to 1 under all percentages) N = the total number of natural chemicals and compounds including the entire set of elements in the periodic table M = the total number of man-made chemicals. This includes, but is not limited to, the entire CAS REGISTRY (https://www.cas.org/content/chemical-substances), which is the most authoritative collection of disclosed chemical substance information, containing more than 71 million organic and inorganic substances and 64 million sequences. Functional agent = any chemical species that provides some form of beneficial property of the 3-D printing material. For example this includes (but is not limited to) species to improve rheological properties, melting temperature, setting time, hydrodynamics (e.g. hydrophobicity, hydrophillicity, etc.) electromagnetic properties (e.g. phosphorescence, color, light transmission, reflection and refraction etc.), chemical properties (e.g. reactivity, smell, catalytic activity, etc.), mechanical properties (e.g. strength, flexibility, stiffness, fracture toughness, etc.), thermal properties (e.g. thermal conductivity, thermoluminescence, etc.), magnetic properties, and electrical properties, etc. (For other material properties see: https://en.wikipedia.org/wiki/List_of_materials_properties )
Copy and pasted from Thingiverse:
Materials capable of being used as 3-D printed feedstock include: 1. Known natural chemicals and compounds including all organic and inorganic substances 2. @ & from 1 to N 3. @ known man-made chemicals, compounds, and metamaterials including all organic and inorganic substances 4. @ & from 1 to M 5. @ & from 1 to NM 6. @ & where 1 to NM acts as a functional agent 7. @ & where any natural or manmade material is controlled for size from 1 Angstrom to 1 m in dimension (e.g. to account for any size related physical or chemical property change as is well established at the nanoscale) 8. @ & any arrangement of the combinations (e.g. superlattices, metamaterials, core in shell quantum dots, etc.) 9. @ & where a nanoscale collection of atoms (e.g. nanocrystal, quantum dot, nanotube, nanocolum, etc.) is used as a functional agent or filler 10. @ & where the shape of the collection of atoms is altered to adjust properties (thus all geometric shapes, and all known complex shapes capable of being generated by a mathematical algorithm (e.g. fractals)) 11. @ & where the surfaces (both internal voids or external surfaces) are adjusted (e.g. roughening) to adjust properties. 12. @ & at any temperature from 0 K to infinity (or any sequence or combination of temperature) 13. @ & at any pressure from 0 bar to infinity (or any sequence or combination of pressure) 14. @ & printed in any environmental medium [NM] (meaning that some 3-D printing materials may need to be used under vacuum, under water, etc.) 15. @ & printed with the assistance of electromagnetic radiation of any wavelength. 16. @ & printed with the assistance of any solvent from N or M or combination of the above. 17. @ & for any physical orientation of the chemical species. 18. @ & for any N or M or combination that acts as a catalyst during the printing process. 19. @ & for any field catalyzed reaction (e.g. magnetic). 20. @ any order of the above.