Harness belts are great for ensuring cat safety whenever it goes outside or for a car ride. The harness belt can be attached to a leash so that your active feline can go for a walk without being able to run off. It also helps keep it in one spot during car rides if you don't want to put the cat in a carrier.
Loop the middle part of the nylon belt loosely across your cat's neck. Cross the loose ends of the belt between the cat's shoulder blades. The buckle end of the belt should be on one side of the cat and the end with the holes should be on the other.
Buckle the belt on the underside of the cat. Tighten the belt to the point where the cat can't wriggle out but still loose enough that it won't choke or be too tight across its belly.
Allow room for two additional holes from where you buckled the belt, then make a horizontal mark with the marker. Remove the belt from the cat.
Cut the excess belt material where you made the mark with the marker. The two extra holes past where you buckled it are there in case your cat gets bigger. Burn the cut end of the nylon belt with the lighter to keep it from fraying.
Make a loop with the nylon belt and slide the loop through the key ring. Put the loop over your cat's head, with the key ring resting on the cat's shoulder blades and the two ends on either side of the cat. Buckle the belt underneath the cat. You can attach a leash to the key ring to walk the cat. Or keep the cat buckled in for car rides by attaching one end of the leash to the key ring and locking the other end in the seat belt.
Consider buying a padded nylon belt for this project because it will be more comfortable for the cat and will dig less.
Do not burn the belt beyond the point of the plastic fusing together or the fibre will start to turn colour.