heat plant material to 2000 celcius with activated charcoal powder. the powder will react wuth the quartz in the plant material to make silicon carbide, a bulletproof material with many more properties.

http://www.sciencedirect.com/science/article/pii/S0008443397000177

oops. meant to post the link above

SiC whiskers and particles have been produced from rice hulls. The process involves three major steps: coking in free air, reaction at high temperature in a reducing atmosphere of hydrogen gas, and separation of formed SiC from excess carbon by wet methods. The processing steps are reviewed and the chemistry of the process is discussed. The produced SiC was added to a molten Zn-5%Al alloy to check its potency as a reinforcing material.