What you'll need:
Needle and thread/sewing machine
Buttons, bows or other embellishments
First, lay your tie out flat and cut it off right before it starts to thicken out. It's OK if the two ends aren't exactly the same width.
Tuck the raw ends inside the tie and pin them together.
Sew that end together.
Measure around your waist where you wear belts. Then measure the tie piece you're working on. Figure out how much you need to add onto your belt before it equals your waist measurement. For example, my belt measurement was 10 inches shorter than my waist measurement, so I need to add 10 more inches to my belt. Make a rectangle out of your excess tie fabric that is twice as thick as your belt and is as long as the length you need to add onto your belt. Add seam allowance to the length and width of the rectangle.
Fold the rectangle right sides together and sew up the longest side. Turn it right side out.
Now cut a piece of elastic that is at least two inches shorter than the rectangle you just made. The elastic is going to go into the rectangle casing you just made and attach to your belt, so it needs to be able to stretch enough for you to put the belt on and take it off by pulling it over your head. You also want it to be tight enough to hold your belt in place.
Feed your elastic through the casing and pin its ends to the casing ends.
Using a zig-zag stitch, sew the pinned casing and elastic ends to the ends of the belt. Make sure you're sewing through the casing, elastic and belt.
Now you should have a loop. You can leave it like this, slip it over your head and show it off.
If you don't want a plain belt, you can add buttons, bows or other embellishments. I added a button to the triangular tie end of my belt.
You're done! Pair your new belt with your favorite flowy dress or top and rock it.