Select "Insert" from left navigation bar, then choose "Rectangle"

Drag a small rectangle out on work area. I like to make mine about 7mm x 7mm.

While the rectangle is selected ensure "Cut" is selected in under "Processing Type" in right nav bar

While the rectangle is selected click on "Array" on top bar, then select "Material test array"

Adjust power and speed parameters, for my wood materials I use power in the 40-100 range, speeds in the 3-12 range(lower for thinner, higher for thicker).

You can add or subtract rows and columns to get more even values on your grid. 

Once gird is ready you can tell it is good when you click on it and under "Processing type" it says *Multiple values.

Frame and process as normal.

Do not leave unattended when doing these tests especially as the higher power can easily ignite your material.