My rendition of a camera strap and hand grip with a few simple items and without additional modifications.
Materials:
*Original camera strap
*weave strap (from a discarded bike helmet)
*small parachute buckles (from bike helmet straps)
*small buckles (from helmet straps)
*1/4" screw (or leg adjuster)
*Picture frame hanger

Note: you can skip the use of the additional straps and buckles and attach the shoulder strap straight to the frame hanger and will work just fine.

Step 1: Instructions

1st. add the parachute buckles to the original shoulder strap, and secure with the pass tru buckles.

I Cut 2 pieces of the helmet strap to attach to the camera and the frame hanger.
For the Camera cut 12" piece that was secure with the pass tru buckles. I put the male parachute buckle on this piece.

For the bottom part (picture hanger) I cut a 6" +/- and secure with the buckles as well.
I put the female parachute buckle in this piece.

*There's a reason why I put the female and male buckle on each end of the straps and it's because when I don't need to use the shoulder strap I can snap the small parts (the ones attached to the camera) and use it like a hand grip. It's better shown in the pictures.

The Picture hanger is pretty sturdy and it's a round and smooth. It's also flat which is good since the camera will be hanging at my hip. It also has two holes so I can adjust if I'm using the shoulder strap or the hand grip.

One thing that you may need to do is make the holes of the hanger a bit bigger, which is easy to do with a drill and 1/4" bit.