Listen and learn, Grasshopper. Nothing is more important that the quality of your product, whatever it might be. What you make, whether it's music or guitar straps, must reflect not the standards around you, but your own absolute standards of excellence. And if your product doesn't meet your own exacting standards, you chuck it in the trash and start over. Never, ever say to yourself, "It's good enough." You must be able, always, to say, "This is really excellent." That is the starting premise of my guitar straps.
I use 3-inch wide 2,000-pound test polypropylene strap material, cut into 6-foot lengths, as the foundation for my straps. I then stitch onto it the material that will show on the front of the strap. I make sure I have a good, long hem on all sides (at least 1/2 inch) so the strap doesn't fray from being pulled and adjusted. Sometimes the covering fabric will be 2 fabrics, a sheer over a solid, which makes for a very interesting look. It just depends on what I'm thinking about making.
After I have covered the front of the strap, I begin my embroidery or beading or whatever I'm going to do to decorate the front of the strap. I begin the ornamentation several inches above the strap end to make sure that I have a good length when it's time to sew on the leather tabs and to make sure the ornamentation isn't hidden behind the guitar. This is, of course, the costliest part of making my straps, not just in terms of materials but implementing the picture in my mind, making it real.
After I've decorated the strap, I hand-stitch the fabric that will cover the back of the strap, again making sure there is plenty of hem length all the way around. The stitching is done by hand because I don't think machine stitches stand up to use and abuse as well. I use a modified double-threaded whip stitch, very strong, very reliable.
When I make my leather tabs, I cut an 8-inch piece of top quality leather, fold it over a commercial grade plastic adjuster, and glue the two halves together using tanner's glue. I then measure and trim the leather to a nice symmetrical shape, punch around the perimeter with an awl, and cross-lace, whip stitch style, through the holes with a heavy-duty waxed thread design for sewing leather.
I set the double slide and thread the strap through it. My final step is to sew the second leather tab on the front base of the strap, again making sure the hem is nice and wide. VOILA! Guitar strap! I hope you've enjoyed this little tutorial. If you have any questions, I'd be glad to answer them. Thanks for reading!