Skeleton mech

Animal skeletons were a kind of organic material, with many unique physical properties; skeletons of mutated lifeforms were even stronger. Some mutants even have bones that were harder than high-strength alloys, and very resilient. Most importantly, they were much lighter than metals - a very crucial property, since lightweight materials could greatly reduce the burden on the mech’s engines, and would substantially improve the mech’s automotive performance!

However, skeletons, unique as they were, did not come in a consistent form, and processing them was difficult; one can imagine how hard it would be to mold them into the various parts of a mech. Even if they could be shaped into appropriate parts, the ingrained surface of the bones often led to uneven force distribution among the parts, thus reducing their resilience and introducing a random factor to the quality of the parts.