The Injury Machine and the Injured Party

The Injury Machine is a large block of marble and brass.
Through its centred is drilled a hole. It is big enough around to fit two heads side by side, and deep enough to go right through.
If inspected with light, the walls of the hole are covered in a fine mesh of interlocking brass plates.

The Injury Machine gives you injuries.

I was going to put a picture of a heavily injured hand here but I figure it might be too much for some people. Look up "machine injury" in google images. Here is a crying child instead.

Insert a limb, head or other body part into the hole and the Injury Machine comes alive. The brass plates ratchet back, revealing hundreds of delicate pincers and scalpels and instruments stranger still.
They descend on the flesh, flensing and lacerating the skin and muscle and bone into horrific shapes and structures, each application unique.

The Injury Machine does not hurt you.

The Injury Machine does not really damage your body. It is simply cosmetic. Your shattered vocal cords tremor to speak from your open throat. The fractured bones in your lacerated hand jostle just so to hold your drink. Your frostburnt legs tremble yet hold your weight. The blood and pus and oozing lymph you leave behind is real and yet you do not fall shivering from blood loss on the floor.
The injuries granted by the Injury Machine do no real damage.
The process can be reversed by replacing the body part in the machine.

The Injury Machine will heal you.

Place an injured limb, head or other body part into the hole and the Injury Machine will come alive, sewing a broken bone into fresh flesh or undoing the ravages of leprosy. The Injury Machine does not really heal your body. It is simply cosmetic. Your healed voice dies wheezing in your mouth. The faultless bones in your unmarked hand cannot clutch a glass. Your new-replaced leg collapses beneath your weight. No blood pours from your wounds and yet you feel your life ebbing away.
The Injury Machine neither heals nor harms.
The process can be reversed by replacing the body part in the machine.

The Injury Machine belongs to a man named Sir Reginald Heely.
He keeps it in his parlour, imported at great expense from the Temple of the Beggar-Saint in a far-flung region of the world.
Every month or so Sir Reginald hosts the Injured Party, a celebration that has become quite chic among the upper classes. Party-goers sport an array of grisly injuries. The ability to maintain etiquette whilst, for instance, your neighbour's jaw hangs by a thread of ruptured skin, is taken to be the greatest test of fine breeding.
Ever the eccentric, Sir Reginald has taken to displaying his finest injuries in public in the dead of night. Many people have been scared half to death witnessing his shambling form from their windows in the moonlit dark.