Ideas for plotting
Plotterfun-classic: turning images into vector art - try 'linedraw', very cool result
Plotterfun pen-width: turning images into vector art - instead of drawing squiggles, the pen width will be modified.
Plotterfun-color: turning images into vector art with colors - try 'linedraw', very cool result
drawingbots.net: a lot of tools to create line art.
maker.js: create modular line drawings like signs, boxes, wheels.
templatemaker.nl: create line drawings for boxes.
dafonts: free font for stencils