I'm assuming you want to make one for your girl friend. Female chastity belts can be made with leather strips or straps. The tools needed to create such a belt would be a hole-punch, a hammer, two suitcase-size locks, and good pair of shears. Fit the first strap around your waist so that it overlaps by 2 to 3 inches in front of your body. Mark and cut it. You will wear this around your waist like an ordinary belt. This should not be a soft leather, as the purpose of the strap is to prevent any self satisfaction from being gained when alone.
Second Strap
The second strap fits up between your legs and snugly against your body. One end of the strap will be pulled up between the legs. It must overlap the strap around your waist, in the back, centered with the tailbone. The front end of the strap fitted up between the legs will overlap the front of the waist belt, centered around the belly button.
Once you are confident in the length of the strap, take the waist strap off and lay it flat on a table. Align the back end of the belt with the waist belt, the area of the belt that aligns with your tailbone, take a hole punch and a hammer and drive the hole punch through the center point of both belts. You can then loop a suitcase lock through the two holes connecting the belts. Follow the same instructions to connect the front of the belt.
In addition to the holes connecting the belts, cut smaller holes in the front of the belt looped between the legs. These holes should be tiny because you are not allowed contact with any part of your body that might bring you pleasure, but the holes must be present to allow for the flow of air and the escape of any bodily fluids.
You can dress up and decorate your leather chastity belt with something as simple as chains, like the kind of gold or silver rope chains you wear around the wrist. Loop them around the front, hip corners or rear of your chastity belt.
Hope this helps. Good luck and have fun with her ;)