Galalith is a plastic made from cows milk. Used a century ago to make plastic jewelery.
Adolph Spitteler patented Galalith in 1899, often called milk jewelery. Jewelery made with Galalith can be found in some antique stores, as well as on line. Sellers for Galalith sell to collectors of this medium. Galalith collectors often collect jewlery and buttons made from milk.
With a little googling you can learn how to make jewelery out of cows milk yourself.
A company in France makes jewelery out of human breast milk, selling as keepsakes of both childhood, and motherhood. story