Piglet is a Piglet is a 2-D engineering drawing editor that supports
hierarchical object description.  It is inspired by Hewlett-Packard's
proprietary HP PIGLET (Personal Interactive Graphic Layout EdiTor),
which later became the commercial Graffy editor by DURST CAD. 

Piglet was widely used for PCB design, Integrated Circuit design and
Microwave thin/thick film circuit development.  In the days before
Powerpoint, Piglet was also used for generating presentation slides. 

Piglet is a very nearly complete, from scratch, implementation of the
original HP editor.  It has unlimited hierarchy, unlimited layers, a
versatile SHOW command for filtering the layers displayed. 

Piglet supports polygons, rectangles, circles and lines.  Piglet reads
autocad SHP font files and can output editable drawings in postscript,
GERBER, HPGL, DXF, HTML, SVG and pdplot(1) formats.  SVG files work very
will with powerpoint and openoffice presentations as a vector graphics
format.  It can also output screen captures in PNG and GIF format. 
There are very complete man pages for all the commands. 

I've used piglet to design several integrated circuits, PCB boards and
lots of CNC projects.  Exporting drawings using autocad fonts as pdplot
coordinate files can be trivially edited into G-code, or used with my
velocity profiling program "velo(1)" for directly driving stepper motors
for engraving projects.  The filled fonts look very professional. 

Piglet is small and lean, fitting on an old fashioned floppy (without
the huge directory of SHP fonts).  It is written in C and Xlib is a good
readable/hackable example of a well-thought out professional graphics
editor circa 1986.