Myself Ana Laura Cantera https://www.analauracantera.com.ar/biomateriales
In this recipe, we use used yerba mate after drinking the mate.
Mix all the ingredients together (Gelatin, vegetable glycerol, water and yerba mate).
If you want a flexible bioplastics, you can crush the yerba mate before using.
Put all of the mixture into a cooking pot and heat it on the stove for 5 minutes, on a slow, low heat and stiring the whole time.
Then let it cool down from a hot to warm mixture, and then pour it on a plastic or metal surface with borders to avoid any spills.
Let the mixture cool down futher, and then use a straw to blow into the liquid. You have to blow in a soft way to generate bubbles. Be careful only to clow air outwards and not suck any air (or mixture) inwards up the straw.
Let th mixture dry. Repeat the steps until the mixture sets and the texture of bubbles has the desired effect.