They aren't stamped really. They drawn over a mandrel and then a second die is rammed down over it to form the bottom flare and pinch the top. A third die trims the bottom flare to size. They are made from brass and then nickel-chrome plated. There are metal fab shops that make brass grommets so could likely make the bell spacers too. I'll bet someone with more time than me could source them but be prepared for probably a 10,000 piece run to justify the cost. I hope someone can take it on