Essentially what my friend and I did is we got to Titanium, and basically started to use just like copper. Just buy some when you need. We're making are way to 100,000 gold very quickly. (2/17/2017)
I already have.
https://itch.io/t/61457/how-to-make-tons-of-money
Just make greatswords as well, and once you get two the point where you have twice the amount of gold of the next ingot type, buy one. This will allow you to be steadily making money and eventually be able to mass buy Titanium without have a serious economic issue.
P.S. I have now breached 500,000 using this tactic. My friend have and I saved, bought 10 of everything 10 times, and then opened the crates to try to make the game crash. Obviously we saved the game so we didn't stay like that. And surprisingly it didn't crash, that means your game has a perfect engine. 10/10 would smith again.