The push to ban standard magazines is insane. It is easier to make a 30 round magazine than it is to grow a marijuana plant. The left is pursuing an unachievable result that will not help stop mass murder.
Rifle magazines are made from plastic, steel, aluminum, or fiberglass. There are 100s of millions of them in existence in the United States. They are easily made at home. They are just a box with a spring. If you have a few 10 round magazines it is easy to convert them into 30 round magazines. Technology has improved to the point that a person can print out functional AR-15 magazines at home.
Before that, magazines were easily made of sheet metal. Of course, there is little incentive to make a magazine when they are easily purchased. If standard capacity magazines are mindlessly outlawed as they were with the Clinton assault weapon ban, the cost for factory magazines increases and the incentive to make them at home increases substantially.
Printed AR-15 Magazine Loaded
Printed AR-15 Magazine in Rifle