What is the upper limit to the strength of a material made of baryonic (e.g. 'normal') matter? Researchers are discovering new and stronger materials every year but is there a limit that they will reach before they cannot make another material that is stronger? There are some very impressive achievements out there, such as graphene, but I believe it is possible to make even stronger materials.
(I mean strength as in the best combination of melting point, hardness, yield strength, tensile strength, toughness, and stiffness)
P.S. Also, no 'exotic' material would fit the bill, such as in neutron stars or quark stars.