I used to love these! These machines had a thin roll of metal and stamped out your message as you painstakingly moved the finger around the letters of the alphabet then pressed down hard on the lever on the right hand side.
The machine then delivered your message on a short length cut off the strip. Totally useless, you couldn't really do anything with it afterwards but put it in your pocket to gather fluff, but as a kid I used to love spelling my name out and getting a metal label! They were totally mechanical - if you didn't press hard enough on the lever that particular letter wouldn't be well defined. They worked on the same principle as (and were forerunners of) Dymo labellers.
They were often found in railway stations - this example is from the railway museum at York.