First you have to have the walnut shell prepared. For this you have to wash it with water, wait for it to dry for two days in the open air. Then it is crushed in an electric grinder and sieved according to the size of grains that one wants.
To make the Thermoplastic Starch: In a cooking pot, add the potato starch, the glycerin, the vinegar and the water, stir until the mixture is homogeneous.
Put over medium heat and wait for bubbles to start to appear, remove from heat and add the Nutshell.
Pour into the mold, wait for it to dry to unmold. Then put it to dry in a dehydrator for 8 hours at 40ºC.
This composite material is made with walnut shell grains larger than 0.3 mm.