Introduction: Herb Graveyard

About: Artist in Residence at Pier 9, currently exploring a vast array of new tools with which to injure myself.

Turn the unsightly bare earth of your herb garden into a charming old cemetery by planting mini gravestones!

This is a simple, if slightly morbid, way to make use of the patches of soil that are visible before your herbs have sprouted. It also provides attractive labels for the herbs once they are fully grown.

Creative property disclaimer:
The idea for this project came from a discussion with TangerineBadger many weeks ago. Thanks for the idea, TB!

Step 1: A Long Blather About Methods

There are many different approaches you could take to making the gravestones in this project: modeling clay, building up layers of card or art foam, wood carving, actual stonemasonry, laser etching, 3D printing... The list goes on.

Depending on your resources and technical ability, not all of these will be possible. I appreciate that not everybody has access to a laser cutter or a 3D printer or the software experience required to design vector files for use with these machines. I chose to use a laser cutter to make my gravestones because:
  • (a) I had access to one,
  • (b) I believed it would give a result with a very high level of detail with minimal effort on my part, and
  • (c) it meant they would be reproducible so that I could refine the process or make more to give away as gifts.

I also believe that excellent results could be achieved using cheaper and more accessible methods, but possibly at the expense of time and effort. For example, you could quite easily sculpt little gravestones out of Sculpey, but it would likely take hours of carving and a very steady hand to get the fine details right. If you're more inclined toward woodwork, the same applies.

If you're comfortable using graphic design software but don't have access to a laser cutter, then I'd suggest one of two routes:

  • Option 1) Design the gravestones you want, then print out templates that you can use to hand-cut layers of a thin material such as wood or art foam. This way you can build up a single gravestone from multiple layers, much as I did. Bear in mind that this method will add material to your gravestone with each layer, rather than subtract it like a laser cutter will.
  • Option 2) Design the gravestones on your computer, then use an online fabrication service such as Ponoko or Shapeways to turn them into actual objects. This might seem extravagant, but there are now many competing services aimed at providing cheap 3D fabrication to the consumer market. All you have to do is send them your image files and choose your materials and they'll send you the finished item in the mail. Yes, we're living in the future. You think of stuff and strangers make it appear. That's the kind of crazy world we live in. Get used to this, because soon kids will think it's normal.

If you're going for Option 2, then you could choose either to print out layers of thin material (as in Option 1) or to print out an entire 3D object. The latter would require you to design the object in a 3D modeling program, which sounds scary but is not nearly as hard as you might think. Really, if you're comfortable designing 2D images using vector graphics, then it's only a small step to learn how to extrude those 2D images into simple 3D meshes.

The rest of this Instructable will deal with how to make gravestones using a laser cutter and acrylic sheets.

Suitable Software

For 2D design, I recommend using a vector-based program rather than a raster-based one: For 3D design, possibly in conjunction with the above 2D design programs:
  • Free:Blender (complicated, but extremely powerful), 123D (simple, but specifically designed with 3D printing in mind)
  • Not free:Maya, 3DS Max, AutoCAD, Rhino 3D. And boy, some of these are very not free.

Before anyone points it out, I realize that several of these software packages are made by Autodesk, the new parent corporation of Instructables. Have they asked me to actively advertise them? No. Am I more inclined to suggest their software because there's been so much talk about them here at Instructables recently? Maybe. Do they make a lot of very useful 3D design software? Definitely.

Step 2: What You'll Need

  • 3/8" white acrylic sheet, suitable for laser engraving
  • Black and white acrylic paint
  • Computer-controlled laser cutter
  • Extractor fan and fire extinguisher
  • Paintbrush
  • Freshly planted herb garden

Step 3: Sketch Out Some Designs

Start by deciding which herbs you'd like to grow and doodling some rough ideas on paper.

I wanted each one of my gravestones to incorporate the shape of the actual herb it was marking, while also resembling something you might find in a real graveyard.

Step 4: Draw the Gravestones As Vector Images

Use your favourite vector image design software (I used Adobe Illustrator) to draw out your gravestones. As you do, think about how they will be etched by the laser cutter.

The laser cutter works by burning away a thin layer of material in a single plane on the surface of a sheet of acrylic. By burning away successive layers, you can gradually carve away a 3D object. This is quite a limited approach to 3D fabrication, as it cannot produce complex objects with overhanging features. What's more, it's very slow; each pass of the laser may take several minutes but only remove a tiny fraction of an inch of material depth.

Shade your 2D vector images according to the different depths at which you want to etch them. In my images, I used darker shades of grey to indicate where I wanted more material to be etched away (except for the cilantro stone, where I deviated from this scheme for the sake of contrast).

Step 5: Break the Gravestones Up Into Layers

Next, make several copies of your image and re-color them so that each one corresponds to a single pass of the laser cutter. These images should be opaque black on a white background. These images will actually be used by the cutter as rasters rather than vectors, so any part that is filled in black will be etched away on a single pass, not just the edges.

E.g. If you want to etch an area to six units of depth, that area should appear black in six of these images.

This is a bit of a mind puzzle and requires some careful thinking about what you want to cut out and where.

Your final image should show the outline of the gravestones. Save this as an unfilled hairline-width path. It will be used to tell the laser cutter where to cut completely through the acrylic rather than just etching the surface.

Step 6: Bring Out the Laser

Fire up the laser cutter, turn on the extraction fans and have the fire extinguisher at the ready. If you don't know how to use the laser cutter safely, find someone who does and bother them until they agree to help.

Place your acrylic in the laser cutter, align it to where the images will etch and start etching!

Between passes of the laser, check to see how deeply the material has been etched. I found that the white acrylic I used was very resistant to deep etching, so I actually had to etch each individual layer six times. This took a looooong time.

Be careful not to move the acrylic sheet in between passes of the laser, or the successive passes will not be aligned.

Once you're happy that everything has been etched away correctly, do a final pass using the vector outline image you made earlier. This should be done on the appropriate laser mode to burn right through the material.

Remove your neatly cut little gravestones and turn off the laser cutter. Don't forget to empty out the debris bed and give the lenses and mirrors a clean with the appropriate wipes and cleaner.

Step 7: Paint the Gravestones

Using watered down acrylic paint, hand-paint the gravestones to give them that aged stone look. I started with a wash of very watered-down black acrylic paint to bring out the details, then built it up from there.

Step 8: The Finished Gravestones

Mmmm, lovely. Stand back and be proud of your gravestones for a while. When you're done, go and plant them!

Step 9: Individual Close-ups

Oh, OK. Take a little bit more time to examine them all in detail.

Step 10: Plant Them in the Ground

Replace your current herb markers with your new gravestones. Alternatively, plot out a brand new herb garden in the shape of a series of tiny graves...