My wife is Hispanic. We travel to Mexico 3-4 times per year. She has traveled and crossed the border many times since the early 80’s. Going south into Mexico is not difficult, at least not at the crossings we use. They are not looking for stuff like metals. They look for a vehicle that is loaded down with too much stuff for two people to be reasonable. You will get taxed for an “excessive” amount of clothes, food, furniture etc. I say two people because that’s my wife and I. It seems to me that the Mexican government does not want “too much” stuff brought in because they want Mexican’s to buy from Mexican’s. It’s kind of a tariff at the border you might say. Now if you have too much, they might unload your truck and then things may be found. Do not cross with stuff in boxes, it needs to be in suit cases and things like that and the older the better, duffle bags. Anything that looks brand new and commercial will draw suspicion and will be questioned and probably taxed at a minimum. If you could not pay the tax, they may confiscate stuff.
The real search and suspicion comes when you head north, even if you are American and have blond hair and blue eyes….and not from the Mexican’s either, from the American’s. They are very suspicious and you better have the mentality that it’s a privilege to reenter the country even if you are a gringo. If you think crossing north is easy, you better change your mentality because they are not friendly to anyone heading north. If you are not prepared mentally, you might get caught off guard and create more of a hassle for yourself, IE search of the car or truck you are driving. It’s a straight face, no joking around situation, answer only the questions asked, no small talk and do what they say. You essentially have no rights coming back into the US and you have better have that mentality.
We once crossed and I had an apple in my back pack. I am a pilot and I got the apple on my most recent trip and forgot it was in there. It was an American apple, I just forgot it. That really almost caused and search of the vehicle and them prodding us through several questions. We nearly had to get out of our truck and allow them to search our vehicle.
If you get nervous, they will be on you like stink on dog doo doo.
Heading south with metal I do not think is a big deal, as long as you don’t draw suspicion starting with how you pack what you are taking and the quantities. Start small, make the move of your metal over a period of time, not all at once.
I think heading south you can be friendlier with the Mexican border guards, certainly not heading north.
Have researched this subject and have found at least one US company that will ship anywhere in the world. Does not eliminate all risks though as customs gets involved in most countries. Shipping to me in Costa Rica no problem except the 30% excise tax they would imposed? . Also a local dealer here swears people traveling in carry substantial amounts of gold and silver coins (even more than $10,000 worth) on their person (in luggage until arrival) with no problems and that is how he gets his stock? Still sounds like a risk with TSA and luggage, but he swears it is no problem.