I have found that the neck strap gets in the way of the viewfinder when using the BG-ED3 vertical grip. Carrying the camera around without any strap is risky, and also very tiring on your hands and fingers.
Thanks to the kind person who put up pictures of the Zing handstrap, I have been able to fashion a similar strap out of commonly available materials. I understand the mass order fell through, so you might want to make your own.
All you need are:
1. The shoulder padding from the shoulder sling of any old camera bag.
2. A no-brand camera neck strap.
3. A tripod quick-release plate
1. Remove the shoulder pad from the shoulder sling.
2. Cut the camera strap to the appropriate size (you will have to estimate how much depending on your hand size - overestimate so that you can cut off the excess later, rather than cut it too short).
3. Thread the shoulder padding onto the camera strap.
4. Cut a couple of holes into the camera strap so that you can thread the screw of the quick-release plate through. Use this to fasten the strap onto the base of the camera. The QR plate clamps the strap onto the camera tightly, so you do not have to worry about the hole fraying and giving way. Make sure to angle it slightly backwards so that it covers more of your palm than your fingers.
5. Thread the other end of the camera strap through the eyelet the usual way.
Viola. You have a home made Zing.