Hi all; Wondering what would be best used as mass filler . I have large quanitys of slate pieces, I also have a large metal pile with auto parts (brake drums , rotors , cly heads , some alluminum), All here in my
yard. I also can get urbanite from
local landfill, apx 1 mile away. I am building a
rocket mass heater not a cobb building and I'm not sure what to use. Thanks for any imput. Tom