I made myself this strap the other day, it was actually pretty quick to make, consists of inexpensive materials, and is really sturdy.
It is a simple four strand round braid, that uses 3/8 inch leather trim. The end was terminated in a crown knot, and after tightening down with pliers, was sealed with super glue.
I made a quick test length to determine how much material was needed with some scrap rope that was the same thickness and width, in the end about 20ft of material made 4ft of braided cord. Remember you are cutting it at half length to start, and using the two pieces across each other to make four strands to braid.
Here is a good explanation and guide to making the braid. http://www.youtube.com/watch?v=0afO40tsqAc
I cut out some soft leather oval scraps using a quarter as a guide, punched a hole through it, and used them as pads against the split rings on the lugs.
It is actually very comfortable on the shoulder and neck, there is a little bit of stretch as well. The termination knot I feel is not too big but is noticeably larger than the beginning end, but I could not find a better option that was as sturdy to lock in the four strands, and nicely end it with split ring attached.
Here are some pics!