Nerf Rival Hera Sling Attachment Point

I really like the Rival line of guns from Nerf. The sub-series of Phantom Corps are just awesome and the [Nerf Rival Phantom Corp Hera](https://amzn.to/2FtaNzP) is beautiful and awesome out of the box.

But there's always room for improvement.

This mod replaces the front sight with one that can serve as an attachment point for a sling. This part was modeled from scratch, but the idea was taken from another user, so I'm marking this as a remix. My mod is a bit beefier and I think matches th