You'll of course need inkscape installed

You'll need an image. .png's work, probably other formats too. It should be as straight as possible. Use a tool like the Gimp to correct rotation if necessary. It should be straight enough so that a line from top/bottom or left/right is straight enough for your purposes.

This assumes that you have a 90 degree routed sample. You'll have to make tweaks but nothing major for something not of that nature.

I am as of the time of this writing us a mix of Inkscape 0.47 and 0.48.

Launch Inkscape and lets get started

Edit ⇒ Preferences

• Pen: Create new objects with: Last used style
• Shapes: Rectangle: Create new objects with: Last used style

Without this every time you create a new polygon you'll have to keep re-selecting things.

And save it somewhere.

File ⇒ Document Preferences

• Grids: Spacing X: 1.0000
• Grids: Spacing Y: 1.0000

• Snap: Snap to grids: Always snap

Without this it will be difficult to get polygons to line up predictably.