Now this is a reason to police your brass…
Using a bucket full of reclaimed old brass, a home handyman created a gold-hued AR-10 lower receiver, with some assembly required.
Nothing really high-tech involved, although it took 60 hours to work out it. Using a greensand mold, he melts down 1,425 assorted casings to form a 13-pound solid block of brass, which he then machines to a 10~ pound blank.
Then, after a lot more milling and cutting, he has a workable lower over the course of a condensed and distilled 20-minute video.
If the concept and the guy seem vaguely familiar, he took 256 soda and beer cans and made an AR-15 last year from their recovered aluminum. Who needs 3-D printing, right?