The global business community has found that standardizing various aspects of how they go about conducting trade is very fruitful in more ways than we are currently able to count. There is a pretty good chance that this standardization is what allows the global supply chain to be as effective as it currently happens to be, and there are plenty of examples of how this level of commonality is aiding newer businesses in entering niches that would have previously seemed like a pipe dream for them to start expanding into.
The truth of the situation is that metal cards have been created with a standard format as well. This is because of the fact that this format helps you to focus on designing the business card according to these specifications instead of having to come up with unique margins each and every times which can complicate matters by several orders of magnitude. Based on our findings, the official format for business cards is three and a half inches in width and about two inches in height, so you should stick to this if you want your card to end up looking right.
With margins like this, you can add any amount of information that you see fit. However, the fact of the matter is that adding too much info to your card can make it look really cluttered and no one would ever want to look through the mess to see the data that is actually important. Keep the additions to your card at a minimum so that the truly essential things manage to shine without any distractions getting in the way of that to any extent at all.