Styrofoam in a blender They are put into a blender with enough added water to float the squares near the top. Blending for about 1-2 minutes and then draining in a sieve will give you a nice Perlite substitute. It has the consistency of coarse sand, but very lightweight.
❧ Papercrete. use 1 3/4 parts paper well pulped, 1 part portland cement, and 1/2 part perlite. Seems to make a very strong mix. After making the mold for the larger square containers I am working on more molds. The largest containers are 11" X 19" x 5" Thank you everyone for the inspiration!