I have not had many issues with things like this really, other than he odd "can you make me a sword folded 1000 times, they can cut right through an anvil you know". In those cases I just tell them that isn't physically possible, and if it was they probably would not want to pay the cost to make it. On the dealing with unstable customers part that is a bit different. Just last month I had a guy asking me repeatedly if I would make a titanium machete for him. He was very persistent and said " I will give you like 75 bucks man." He said he needed to clear some brush at his farm. When I finally told him I could not do it at his price point, and asked why he would not just buy a cheap one at a store for his one time project, he said its because he can't legally buy weapons in a store due to some previous crazy thing he did. I ended it with saying I couldn't do it for his price, and could not get steel that big so I was not able to help him in any way. He said that was fine and hasn't bothered me since. I have known the guy for some time now, and never would have though he was a danger, but it just shows that you never really know who you are dealing with these days.