Usually in industrial design when you select a material you do so based off a constraint selection process: https://en.wikipedia.org/wiki/Material_selection htt

Usually in industrial design when you select a material you do so based off a constraint selection process: https://en.wikipedia.org/wiki/Material_selection https://en.wikipedia.org/wiki/Material_selection Typically you have material specific constraints (workability, cost, ease of sourcing) and application constraints (for a phone case this would be weight, stiffness, min/max dimensions things like that). Once you have determined the constraints you can solve for the objective function using numerical methods i.e. Solve all the simultaneous equations. That will identify the materials which are most suited to the chosen application. And will eliminate materials with drawbacks that cause them to fail to meet the constraints (so you don't end up with a iphone case made from diamond which costs a fortune or from ceramics which weigh a tonne).