It is possible to lock a non-locking strap or cuff, if it has a suitable buckle and you have the right sized padlock.
The image to the left is a closeup of me, posing in my favorite hip harness that I use for so many of my bondage predicaments. The tie usually starts with some kind of loops around my package that is then pulled between my legs, up my butt-crack and tied around my hips (below the waist, but just above the hip bones). The tail then goes back through my legs, back-to-front, through the loops around my cock, over my package (splitting the balls), and tied to the ropes around my hips.
The images below are closeups of a rope harness that secures a steel cuff around the male genitals so it won’t slip off when used to immobilize or torment the person wearing the harness.
Now I have a video I call “Harness Talk”. You can check it out here.
The harness starts with a loop around the base of the genitals (where you would put a cock ring) and continues through the legs and between the buttocks, then around the waist such that the rope is pulled tight between the wearer’s butt cheeks. I made two wraps around the waist for this harness, using reverse tensions in back (not pictured).
The handcuff goes around the genitals where you’d put a cock ring and under the rope harness lines that go between the legs. That keeps the cuff from pulling away from the body. The briefs may not be absolutely necessary, but they do protect the tender underside of the genitals from direct contact with the steel cuff, and they enhance the crushing effect, since they capture the cock and balls.
The final step is to take the loose end of the harness rope that is tied off in back and bring it back through between the legs to the front, thread the rope through the original loop around the crotch to keep it centered, pass it over the genitals, splitting the balls, pass it through a link in the chain (for this you need a thinner cord/rope … I used 3/16″ here), then tie it tightly to the wraps around the waste, such that the top of the cuffs are also held to the body and the ball splitting crotch rope is good and tight.
