In this latest video of Brian at Echo1, he shows how to build a custom Magpul M4 AEG with an Echo1 M4 AEG as the base gun. The first thing you need to do is, of course,  to have the Magpul PTS MOE furniture kit before you start the project. It's a pretty much straightforward thing to do which you can do in under 7 minutes. But if you're think it's still a hard thing to do, then watch the video below.