Can/How Can I buy Copper and/or Tin Bullion?

People invent in precious metals because they have intrinsic value that will remain, even after say a nuclear Holocaust.

While gold/silver have a lot of value, I was thinking that I could probably do better with copper and tin, they are easy to work with, and you can make bronze quite easily with them. I am aware that buying copper and tin is a poor investment decision, and won’t really help me in a survival situation, but what I want to know, is it possible to buy bars of copper and tin (say one or two), and where would I do it?

I say again, I want these bars purely for fun, not as any rational investment. Thank you.