Okay. So this is neat. It’s like concrete but it is made out of repulped paper fibers. They call it papercrete. It isn’t approved as a valid building material, yet it is being used by homesteaders and preppers alike because of its durability and strength. It is relatively easy to make and doesn’t cost much at all!
It could actually be made using recycled paper if you really wanted to be cost effective about it. Check it out for yourself in the link below and maybe even make a block or two!