In the back of the store you see a strange machine labelled "Cloning machine". There's an empty booth, sealed by a glass door. There's a coin slot, a control panel, and a set of instructions.
You put a quarter in the coin slot and a helmet lowers down. Instructions say "Put on helmet and touch finger to pad." You do it and there's a buzzing in your head. Then a needle comes out of the pad and pricks your finger, drawing blood.
You withdraw your finger as the helmet raises again. You decide to read the instructions--maybe you should have read them before starting the machine up, but it's too late now.
"This combination of advanced science and powerful magic lets you create an exact copy of a person, using a blood sample and a brain scan. In version 2.0 you can change the copy so that it's no longer exact." There's a diagram of the control pad and screen.
You see that you can make any changes you want. You can make a copy that's the same as you except that it's the opposite sex, or except that it's 6 years old, or has blue fur. You can change its sexual orientation, or make it like eating spinach-flavored ice cream, or just make it obey you. You can even combine them, so you can make a copy that's just like you and knows anything you know, but is a year older, lesbian, speaks Italian, and can lift 500 pounds. However, once you make the copy you can't put it back in the machine.
You go to the control panel and tell it what changes you want to make.
Inside the locked booth, the needle drips the drop of blood on the floor. Then strange colored rays inside the booth flash out and hit the drop of blood. In a few seconds, it grows into the copy you asked for and then the booth opens....