Lebensweker “Life awakener” invented by Carl Baunscheidt. This was a quack medical instrument widely used in Europe and America in the 19th century. Pulling back and releasing the spring-loaded mechanism would puncture the skin with a number of sharp needles. The theory was that this would act as a counter-irritant which would distract the body’s focus away from the main injury.
Iron slave collar, Roman, fourth-sixth century CE The inscription says "I have run away; hold me. When you shall have returned me to my master, Zoninus, you will receive a gold coin". This was sealed around the slave's neck so there was no way to take it off.
Chastity Belts (1400s-1930s) Chastity belts were designed to keep women "pure," preventing consensual and non-consensual sexual intercourse (and masturbation) by enclosing the genitalia in a shackle-like contraption. The belts, typically made of leather and metal, featured a locking mechanism and included small holes to allow urination and defecation -- but nothing else.