Perlite, Sphagnum Peat Moss, Portland Cement, Water, Cooking Spray (I used Pam), Large bucket or something to mix your ingredients in, Rubber gloves, Particle mask, Safety glasses, Various plastic or cardboard containers to use as molds
Wear your rubber gloves, particle mask and safety glasses!!! Portland cement can be nasty if inhaled, gets on your skin or in your eyes. Don't make me come over there and put them on you!
Mix equal parts of Perlite, Sphagnum Peat Moss and Portland cement. Add enough water to make it a cottage cheese like consistency.
Spray your containers with cooking spray and then fill the areas between the two items with the mixture.