Here is the tutorial I have been working on for you guys. These are really simple to put together and you can adjust the measurements to fit whatever size you need.
(2) 21" squares of cotton fabric
(2) 2" plastic rings
(1) 41.5" x 3.5" strip of cotton fabric
Take your 2 squares of fabric and place them right sides together. Using a 1/2" seam allowance, sew around all 4 sides leaving an opening for turning.
[attachment=8:24jd68zt]half inch seam allowance.jpg[/attachment:24jd68zt]
Turn your fabric right side out so that you now have what resembles a flat pillow.
[attachment=7:24jd68zt]turn right side out.jpg[/attachment:24jd68zt]
Stitch the opening closed.
[attachment=6:24jd68zt]hidden stitch to close.jpg[/attachment:24jd68zt]
Using a 1/4" seam allowance go around all 4 sides completely.
[attachment=5:24jd68zt]quarter inch around outside.jpg[/attachment:24jd68zt]
Fold the long piece of fabric right sides together and using a 1/4" seam allowance sew a tube.
[attachment=4:24jd68zt]sew strap seam.jpg[/attachment:24jd68zt]
Press seam open.
[attachment=3:24jd68zt]seam press strap.jpg[/attachment:24jd68zt]
Turn right side out and press flat.
[attachment=2:24jd68zt]strap turning.jpg[/attachment:24jd68zt] [attachment=1:24jd68zt]strap right side out.jpg[/attachment:24jd68zt]
You can use a decorative stitch if you want to secure the layers so your strap won't turn and will always stay flat.
[attachment=0:24jd68zt]stitching on strap.jpg[/attachment:24jd68zt]