Hey all, I've been running a AE Mk1 for a number of years and always hated that I was limited to to 5 round magazine. Supposedly AI made some 8 round mags but I've never seen one nor know anyone that has. I'm a CAD designer by trade and do a little home 3D printing on the side for fun. So I designed and 3D printed the main body and removable floor plate. Slid the stock floor plate off and just slid the extension on and retained it with a screw. I then ordered a MDT AICS spring that is is needed when using their mag extension. The hard part was modifying the MDT spring and follower to fit in the single stack Mk1 mag but it was pretty straight forward once I got into it. Here's what I ended up with. An AE Mk1 mag that holds 10 rounds ( 11 if you really force it ) ! I'm pretty excited to put it through it's paces and make sure it's reliable. I've cycled through my AE multiple times without any problems. Hopefully it holds up at it's first match next month.