Mix the 15 grams of agar agar, 250 ml of water and 5 ml of glycerol
Heat this mixture and stir until the begins to bubble and it becomes a homogeneous thick paste
Next turn off the heat and add the coffee chaff/husks. Make sure to mix the ingredients well so that all of the husks are connected by the paste
Prepare your mould to be clean and dry, then spoon or pour the mixture into the mould. The drying time will depend on how well the mould is ventilated and how warm the environment is too (whether drying in an oven or air-drying).