Start by Creating the artwork with drawing software.  We use Corel Draw, others use Adobe illustrator

Then print the design onto template paper fed through a plotter.

As you can see we made wooden extensions to hold the big roll of paper away from the plotter.

The plastic keeps it dry.  (it is near our carving stations)

Printed 20" x 40" template

We found the plotter on Ebay for $600 delivered

It is an HP DesignJet  750C