DIY assembly instructions for the Hempcrete Stool by Ian Anderson. In making this stool, you will be producing an unconventional yet efficient building material with both insulation and thermal mass properties. Made up of hemp hurd, lime, and a binder material, hempcrete (as a single material) is a natural and carbon negative alternative to the abundant layers of insulation, drywall, cladding, etc… that cover the walls of our homes today.