Properly wash the potatoes and make sure no dirt remains on them and then peel the potatoes. To make things easier for your blender, cut the potatoes into smaller cube-shaped pieces. Add a cup of water and cut potatoes to the blender’s jug. Turn the blender on and let it run for about two minutes at the highest speed setting.
After the potatoes have been blended, strain out the cloudy water into a bowl using a coffee filter or something similar. Be sure that only blended white potatoes remain in the filter before moving on.
Take a small container and add one-half teaspoon of baking soda and two tablespoons of water to it. Set aside the container for later use.
Add about 7 tablespoon of cold water and 1 tablespoon blended potatoes from the blender, 2 teaspoon of white vinegar, 2 teaspoon of vegetable glycerin and 5 drops of food colouring, one after the other in a pan. Place the pan over a stove burning at low heat. Start stirring the contents of the pan until the mixture becomes fairly thick. At this point, turn the stove heat to medium and continue to stir. Add the mixture you prepared in Step 3 and let the contents of the pan boil for about 10 minutes.
Pour the mixture in the pan onto an aluminium foil and allow it to dry for about one day in a sunny room. To speed up the process, consider drying the mixture in an oven preheated at 150 degrees Fahrenheit for up to two hours.
When the mixture dries, your potato plastic is ready and you can mould it into any desired shape or form.