Balloons, once made from dried animal bladders, are now made from latex, and the process of making them is fascinating. First, the latex is mixed with dye for 16 hours. While that happens balloon moldings are dipped in a chemical which attracts latex, then into the latex itself.
The balloons go through several other physical and chemical processes before going through stress testing with a sort of air faucet. There you have it, baloons!