Made a stand for my airsoft M4, so now i can forget about problems with proper displaying them. It's uses 20 rds mag because of print area of my duplicator, but can build same thing for 30 rds mag. I used model from here: https://grabcad.com/library/ar15-10-15-20-and-30-round-223-5-56-magazine-stl-s and added a base. If you have plans on using this model for realsteel m4, than better use ABS, at least 50% fill.