I wanted to accentuate the heavy black lines in the artwork, so I pretreated the plywood with a one part borax to ten parts water solution.  If you want more subtle lines skip this step.

Mix the borax into hot water until dissolved.

Paint the plywood with the solution trying for an even cover.  It should have a wet sheen but not be dripping.  The lower portion of the wood in the photo shows how the wood should look.  A surface sheen but not dripping.

As soon as wood is surface dry, flip over and weigh down.

Let sit overnight.

Download the file and process.  Layer 2 is to be cut.  Layer 1 is to be engraved.

If you used the borax solution, spray a layer of clear coat on the coasters immediately so they do not smudge.  Be sure to do this outside so the fumes don't kill you.

You can finish the coasters any way you want.

I used Sharpie fine point and Arteza acryllicncolored markers to “paint” the coasters.  This was followed by two more layers of clear coat.

If desired, affix little rubber feet to the bottom.