Lay out your shelf liner over your work surface, lining up one of its edges with the edge on your work table that is closest to you to create a non-slip surface on which to lay your pendant when you clamp it. The size of the liner and the location of the other edges don't matter as long as the liner itself is lined up against your work surface's edge so you can easily clamp down your pendant.
Set your glass pendant on the edge of your work table where you've laid out shelf liner.
Draw your design or write your message on the pendant, using your dry erase marker. Place an image behind your pendant before clamping it to the table to easily trace it onto your pendant. Clamp the pendant to the table.
Trace along your drawing with your engraving tool. To use your engraving tool, grasp your hand engraver in your dominant hand, holding it between your index finger, middle finger and thumb. Pick at your pendant with the engraver, using short, pressurized movements.
Wipe away the glass dust as it accumulates. Remove your pendant from the clamp when you've engraved your pendant to your satisfaction.