This pattern is for a little kids' belt and can really be adjusted to suit your needs. You will need 2 "D" rings (found in craft/sewing stores) for each belt you wish to make. The ones I used are 3/4". Crochet hook "G". A tapestry needle for sewing D rings on and weaving in yarn ends. Yarn can be anything you wish, really...it takes a small amount- way less than a skein. In the picture I used Vanna's Choice "purple mist" worsted weight yarn.
(if your rings are smaller/wider, add or take away the number of chains so that it will fit the flat portion of the D ring).
For 3/4" D rings: ch 5, turn.
Row 1: hdc into first st and next 3 across. Ch 1, turn.
Row 2-??: repeat row 1.
After you have reached the desired length (making sure your belt will fit around and overlap by several inches), fasten off, leaving a 12 inch length of yarn for sewing in the D rings. Go back to the other end and weave in the beginning tail. Push both D rings onto one end of the belt and overlap to itself, using tapestry needle and the 12" tail, sew to itself very strongly. Weave in the end when finished. (the example in the picture is 86 rows and fits approximately 3 to 6 years old).
Ta-dah! Very, very simple and at this point you could really do any embellishments you wanted (for example if the belt won't have to go through belt loops, like wearing over the top of a long shirt- you could put flowers onto it or whatever you like). You could also use different stitches than the HDC if you wanted for different "stretchinesses" (is that a word?) and looks.
This is a free pattern- feel free to use it and make a ton of belts...just don't sell the pattern or claim it as your own! I appreciate credit just as I like to give the same when I use others' patterns. :)