I know this may sound like picking too much fruit from the tree at harvest, but I wish these buckle pieces could be made out of 6AL4V Titanium. They are understandably made from a good grade steel, but on the heavy side when you combine two sets per front of a car.
I probably would have fabricated a set or two already if it weren't for my fear of not being able restitch the lap belt folds with the proper stitch material or strength.