NOTE: THIS IS FOR AIRSOFT ONLY. WILL NOT FIT A REAL M4!

Just to satisfy my tacti-cool craving, I whipped this up. Shown on my airsoft SR25. In place of roll pins, I used M3 screws. If your slicer doesn't let you select a flat surface to lay down, manually rotate it 7.3 degrees and the longer flat side on the bottom should sit flush on the build plate.