Been doing that for about the last 35 years, since I was about 10 years old. I do it to every model I build since. Although buying and selling built kits is something that never occurred to me then, I knew I wouldn't live forever and thought it would be cool if my name lived on in the models that I built. Kind of a legacy thing I guess. With the advent of the internet and online model communities, its an even better idea because it's quite likely that someone who knows of you will someday end up with some of your builts, so now when I build a kit my screen name goes on there too.