Materials are the mother of all inventions
A technological problem can always be tackled by considering new materials and their processing technologies. Ceramics, metals, polymers, composites, biobased materials all provide unique properties and solutions, notably for circular solutions (credits to Bert de With)

The stone age did not end because of a lack of stones
The solution to a given materials problem always benefits from zooming out ("always think out of the box") to avoid being stuck in similar solutions (credits to Dick Koster)

Numbers tell the tale
Measurements and modelling provide an indispendable basis for a realistic solution, Life Cycle Assesment (LCA), Capital Expenditures (CapEx) or Operational Expenditures (OpEx) predictions are always part of the solution (credits to Henk van Mameren, Fons Sauren†, Patrick de Jager)

Technology alone can't solve the problem
Technological solutions must be (made) accepted in the full quadruple helix with industry, science, government and citizens (credits to Jan Jonker, Antoine Heideveld)

The icons above are pictures from research into fracture mechanics of ceramics and glass, showing microstructure and fracture origins (defects)