I had the brilliant idea to show a few pointers on making an adjustable ribbon or trim belt I've made for my girls. Then yesterday, while looking at a favorite blog Little Blue Boo I saw that she had just shared the the same idea... but much, much better using velcro. Go there. She is AMAZING!
Anyhow, here is the process for making D-ring belts.
As for measurements: lining ribbon -you need the length of his/her waist plus 4-6 inches
exterior ribbon - length of lining ribbon plus 10 inches
If you have gotten this far, go to LBB and see the real thing.