I'm looking for a simple (free?) program to print 2D geometric shapes for a friend who makes stained glass lamps etc.

All he wants to do is type in the base dimension for, say, a pentagon and a to-scale shape appears on screen with the correct angles etc. which he can then print out. It doesn't have to be exact to the fraction of a millimetre, but good enough to work with.

Any ideas? Tks.