This is a group render of a line of 3D Printable AR-15 lower receivers designed by user Shanrilivan.
Shanrilivan. Originally uploaded to Wikipedia by <a href="https://en.wikipedia.org/wiki/User:ProteusEditing" class="extiw" title="wikipedia:User:ProteusEditing">wikipedia:User:ProteusEditing</a>.
<a rel="nofollow" class="external free" href="http://imgur.com/a/sHGGl#0">http://imgur.com/a/sHGGl#0</a>