You'll need to design your coasters using vector graphics software like Adobe Illustrator or CorelDraw. You can use the attached file as a starting point.
Start by creating 4" squares with rounded corners that will be the outline. Add a border inside the perimeter, this will hide the smoke stains from cutting out the coasters. Finally, add your design in the empty area. You can create your own or import an image. If you want a cut-out stenciled look, use a stencil font like Allerta Stencil
, remove the fill and set a 0.001pt stroke. When you're happy with your designs, copy them into a grid the size of your laser bed.