This Instructable focuses primarily on how to design a laser-cuttable coaster in Illustrator and only briefly touches on how to use a laser cutter. You can either follow along to design your own, or download the pdf/ai file to get laser cutting!
Open a new file in Illustrator. Name it, make sure it is in RGB instead of CMYK, and set the size to the same as the bed of your laser cutter. The Universal Lasers laser cutter I use is 32"x18", the Epilog Zing I use is 16"x12".
I love computer-aided fabrication. Right now, a laser cutter is more accessible for me than 3D printers. While I do have limited access to a 3D printer, it is an extrusion-based (PLA) printer, rather than resin based. With a resin-based printer, I would have tighter control over form and a higher resolution print than PLA/ABS. A Form1 would allow me to rapid-prototype non-flat objects. I would use it to make soap stamps, printing blocks, molds for casting plaster or soap, and hinges/joints/detail objects to use in conjunction with laser-cut pieces.
Step 1: Converting a raster image to a vector image
Finding an image
You can start with any image. Black and white images work best. I began by searching for chlorophyll. If you find an image you like, be sure to find one that is labeled for reuse, especially if you want to sell them.
Using image trace to convert to vector
Copy your image of choice and paste it into Illustrator. Then, click the layer with your image. On the menu at the top, go to object > image trace>make. If you are happy with the results, click expand. Your raster file is now a vector, which means that you can edit the components. Converting to a vector isn't necessary in all cases (especially if you just want to engrave), but because we want to be able to trace around the outside of the image later on it is necessary in this case. You can use the Direct Selection Tool (A) to edit your image if you would like.
Step 2: Making a pattern
I want to have both a patterned background and a larger molecule in this coaster. Because I'm going to cut off the long phytol chain on the main part of the coaster, I wanted to keep all of it in the background.
Select your image using the Selection tool (V) then going to Object > Pattern > Make at the top. A pattern options window will pop up. You can choose how to tile your image and the spacing between in this window. Save pattern.
Make a circle the size of your coaster using the Ellipse tool (L), then fill with your pattern (which appears in the swatches window. I like doing making coasters anywhere between 2.5" and 3.5" diameter.
Step 3: Making a shape outline and offsetting the path
Duplicate your chlorophyll molecule and move to a new layer. I decided to use the direct selection tool (A) to cut off the long chain on my chlorophyll molecule for this part. Make a circle the same size as your pattern circle. These should be the only two images on this layer. Arrange your chlorophyll so that it fits nicely on your circle. I want it to stick out over the edge a bit. Group this layer (G). Click the group, then go to Effect>Pathfinder>Add. Offset path by going to effect>path>offset. A window should pop up and you can use how much you would like to offset by.
Step 4: Layering and putting it all together
Organize your layers! I like to have a raster layer (engraving) and a vector layer (cutting).
Raster Layer (engraving)
On your raster layer, add your chlorophyll and background pattern. This chlorophyll should be the same as your cut outline. Decrease the opacity of the background so that it doesn't interfere with the visibility of the main chlorophyll. You can decrease the opacity by clicking that layer, then clicking appearance, opacity. I set the background to 22%.
On your vector layer, make sure your outline thickness is appropriate for you laser cutter, otherwise it will treat that layer as a raster, rather than vector. Universal Lasers laser cutters prefer a 0.072pt stroke. Double check to make sure you are using RGB color for your stroke.
Step 5: Laser cutting and finishing touches!
Choose your material. If necessary, cut it down to the correct size for your laser cutter (I usually use a bandsaw for this part). I like 1/8 inch birch plywood for a super sturdy coaster.
Focus your laser cutter to your material. Open your file and click print. Make sure it knows to do both vector and raster paths. If you'd like, you can color code your paths (e.g. black for raster, red for vector). Or, you can print your raster and vector separately. If you do it that way, make sure you cut your raster layer first. But, depending on the laser cutter, it isn't always necessary. Different laser cutters require different settings. For 1/8 inch birch plywood, I usually use 70% speed, 100% power for the raster with one pass and 100% power, 50% speed once or twice while cutting. With wood, I like to go a little fast on the cutting layer and cut multiple times if I don't want to edges to char too much. But, that depends on your material choice and laser cutter.
I like to coat my wooden coasters with clear satin Polyurethane spray to make them water resistant. I use satin because it is fairly matte. Make sure you spray in a well ventilated place, like outside or in a spray booth. Wear a mask or respirator while you're working. Follow the instructions on the coating. I usually do two coats, spaced several hours apart, and wait 24 hours until using them.
Please ask if you have any questions!