how to make a hard plastic baseball helmet or at least hard plastic?

i need to no how 2 make a hard plastic helmet for a project or at least how to make hard plastic i doesn't really need 2 b a helmet but at least hard plastic since i need to c what materials absorb the most impact.....if off the top of ur head can u think of words that i can look up as research 4 a project lik dis for example like velocity or impact but in a way related 2 this project...thx

Answer:

Plastics can be formed in several ways including drawing or injection molding. For a helmet, there is a hard outer shell as well as a more compliant inner layer. The outer plastic spreads the energy of an impact over a larger surface area while the softer inner material compresses against your head. Some key words to look for: kevlar, manufacturing, thermoplastic, thermoset (the last two are families of plastics).

complex thing. try searching at the search engines. that can assist!