As part of a biomechanics course aimed at both upper-division Biology and Physics majors, this laboratory exercise introduces students to the ingenious ways in which organisms vary the composition and form of support and defensive structures such as bone and shell to maximize their strength while minimizing the energetic cost needed to produce them. Students design and build physical analogues that take advantage of strategies found in nature such as the use of composites and variations in form and internal structure. These are then tested in a competition to determine whose design can withstand the greatest force with the lowest mass per unit length (a proxy for the energetics of production). From this exercise students gain a better understanding of how these structures can be optimized, as well as providing an opportunity to discuss basic biological concepts such as fitness, variation and evolution.