I know what you mean. I've always loved drawing instruments as a kid (before the days when computers were widely available).



I recently found this in the London Graphic Centre in Covent Garden - that place is serious Mecca for people who love graphic art.

Although it's meant to be used to do 3d drawing, it makes a really good instrument to draw roads at constant widths. it's by no means perfect, but kind of fun to use. It would be nice if it there was a metal equivalent which would be more sturdy.