Under the current state of federal law, anything which might affect interstate commerce can be regulated. The logic in the Wickard case was that his wheat was regulated, even though he grew it for his own personal use, because if he did not have it then he would be buying wheat that was involved in interstate commerce.
This is why the new law is a great symbol but is not really any use. If you build your own suppressor, even with all Texas sourced materials, you have affected interstate commerce by not engaging in it. Thus, Congress can regulate anything and make it illegal.