Step 3: Make And Etch Your Design
Figure out what you want your design to look like. If it's complex, like words, you might want to print it out rather than draw it freehand. However print them backwards (mirrored left to right). This is because we're going to etch the back of the plastic, not the front (it will be brighter this way) and we don’t want our words to come out backwards.
Cut your plastic to size. You can cut it to any size you want but allow at very least 8mm (3/8") on one of the sides--this is the side where we're going to put our light. If you're using polyester sheets you can use scissors to cut. If you're using acrylic sheets it's best to use a power tool with a blade meant for acrylic to avoid chipping.
Put your design on the front of the clear plastic for reference. If you're doing it freehand, you can stick some clear tape on the front and draw it. (Or many plastics come with a protective layer that you can draw on with a marker.) Otherwise tape your printout in position so you can see it from the back and use it for reference.
Etch your design. We use a Dremel with a fine round carving tip at about 10-15,000 RPM and etch to a depth of about 1/2 the thickness of the material. You can also use a needle, knife, or file to mark your design, anything as long as you rough up the surface. (I've even tried sand paper. It worked but it came out very sloppy.)