Pykrete;
Pykrete - Wikipedia, the free encyclopedia
Non toxic torpedo proof water and wood pulp ice polymer.

Trex wood-polymer decking;
http://www.trex.com/
Non toxic wood pulp and plasic polymer.

Cheap non toxic horn deadening. Acrylic Latex plus wood pulp polymer sound deadener; take wife's mixing bowl and mixer, add roof coating and lots of saw dust(the courser the better), mix thoroughly with as much filler as can be suspended in latex to prevent shrinkage, dip horn into or pour in external cavities. $19/gallon.