I got tired of separating brass from steel pin media by using magnets, so I whipped up a simple funnel with a sifter to allow the pins to fall back into the rotary tumbling barrel.. The funnel neck is long enough to prevent it from popping out of a stock RCBS barrel as you fill it, but there is a tiny amount of play in the fit to allow you to vibrate/jostle the print to help the media sift back into the barrel faster. 

I printed this on a Bambu X1 with an AMS, on a Bambu cold plate, using generic PLA.
Colour change is due to spool running out and me foolishly not having any more generic black handy to put in the AMS. :D