Airsoft TM AA-12 Drum

My take on a DIY drum for the Tokyo Marui Airsoft AA-12.

The design is based on a M249 box mag.

You will have to disassemble the box mag and only keep the mechanical parts inside. They should come out as one complete module.
Cut it down to shape and shorten the feed tube to fit. It's all very straightforward and assembly can be done by press-fitting. Refer to the included picture.
Use 3mm pins to hold the lock in place and self tapping screws for the cover (I used some Spaenaur #7 x 1