If you’ve read my process documentation, the general process used for this skull will be familiar to you. I’m skipping the nitty-gritty details as I write this in CE2019 because the details of my process have changed since when I made this skull in CE 2014.
This model was done freehand in Blender, without the benefit of a base model.
Other things to do: Make sure that your grid unit is in inches or millimeters, not generic units, and that the models are scaled before you start modeling. I had to take two hours to get things scaled properly when I realized I was outputting a PDF that was a hundred-odd feet by five-hundred-odd feet instead of three feet by fifteen feet.
Fedex Kinko’s HP printers don’t like the PDFs output by Blender, but their staff desktop computers will accept the PDFs with a minimum of overrideable error messages.