This adapter allows you to use almost any airsoft M4 magazine with your airsoft Thompson AEG. The side-mounted magazine release allows magazines to be easily ejected for quick reloads. The adapter slots into place where a Thompson magazine would normally insert. To remove the adapter, simply lift up on the Thompson's normal magazine release and the adapter slides free.

To finish this adapter, you will need the spring from a cheap ballpoint pen, an 11.4mm length of tube from a cheap Bic pen, and a small nut and bolt. The pen spring needs to be approximately 4mm in diameter. If the spring is too long, you can use wire cutters or flush cutters to cut it down to length. The nut and bolt size does not really matter. Just bring the adapter into the hardware store when you purchase the nut and bolt so you can be sure it is thin and long enough.

The pen tube is used to create the internal magazine feed lips. Previous models had an issue where the feed lips could occasionally snap off if a magazine was inserted wrong. By changing the printed feed lips for a length of tubing from a pen, the durability drastically increases. You can use glue or epoxy to secure the tube in place, but the friction fit should be very tight.

Note: Do not attempt to print this with automatically generated supports. You will need to put support blockers on the internal feed tube that runs through the adapter. If you do not add the support blockers, supports will be added to the internal channel through which BBs travel between the M4 magazine and the hop up. These supports will be impossible to remove.

Due to the policies of CGTrader, I am unable to show the adapter installed into its designated slot or a magazine inserted. It does work, and it works well.