I am going to post a series of pictures. The first one to guess the answer to the question gets the prize, which will be some rep points. 20 sound good? Yup, 20...

lol
Ok, here is the pic:
The question is, what is the barrier on the left side of the tank made of, and what was the method used to create it. Partial answers don't count, you have to answer both parts of the question to get the prize. Good Luck! If no one gets it with the first pic, I will post another, which will be clearer, and then one more if no one gets it then.