Here's the how-to for my banjo/guitar strap cover for SYTYC.
guitar strap (since I don't actually play an instrument, I bought mine here)
48" x 5.5" strip of fabric for inside of strap
multiple squares of fabric of varying lengths, each 5.5" wide
48" x 5.5" strip of fusible fleece or batting
::My measurements are based off my own strap. Since this is a cover that should be able to slip on and off of your strap, double check the measurements of yours before you start!
::And if you're like me and don't actually play the guitar, you could always adjust the measurements and cover a camera strap or belt.
Start by piecing and sewing your patchwork squares together into a strip 5.5" x 48" long (as I said, adjust these measurements if you need to). Press the seams flat.
Fuse fleece/batting to the wrong side of the patchwork strip.
For a quilted look, sew straight lines parallel to the edge of the patchwork strip. Sew the first line 1/2" from the edge, and the rest 1/4" from the previous line of stitching.
An easy way to make the 1/4" lines is to just line up your presser foot with the previous line and use it as a guide.
Hem all four short sides of your strips.
Pin your two strips, right sides together, on the long sides and sew.
Turn the strap right side out, press, and slip the strap inside.
That's it! Now you can rock in style.