How to make a decorative letter with moss or cress growing on it.

Perfect decoration for a garden party, romantic wedding etc.

What you're going to need:

Materials:

- plywood or MDF, about 4-6mm thick and as large as you want the letters to be / as large as will fit in your laser cutter ;)

- coco mat (get it at the hardware store in the plants section) those usually come in long rolls, check the width to make sure it will cover the width of the letter / pattern you plan to lasercut.

- hot glue

- for the moss letters: fresh moss, yoghurt (unflavored / unsweetened)

- for the cress letters: cress seeds, fertiliser for herbs, optionally: vermiculite

Tools:

- laser cutter

- staple gun

- thick scissors

- for the moss letters: kitchen blender

- spray bottle full of water and / or a shower

Step 1: Laser Cut the Plywood / MDF

Prepare the letter(s) or pattern you want to make in Inkscape or another vector graphics program of your choice. Export in the format your laser cutter uses, upload and cut the plywood / MDF.

Make sure to look up the correct laser cutter settings for your material.

Do NOT try to laser cut the coco mat. It will catch fire and create a safety hazard!

Step 2: Hot Glue the Coco Mat

Once the letter has been cut, hot glue the coco mat to it. It doesn't have to be perfect, we're going to reinforce it with the stapler gun anyway.

Be careful to hot glue the mat so that the mat will be on the front side of the letter, and the wood on the back.

Step 3: Cut Out the Coco Mat

With a strong pair of scissors, cut the coco mat, following along the borders of the letter. A cutter can be helpful to poke a hole in the mat if you need to cut out inside parts of letters (like the a).

Step 4: Staple the Coco Mat to the Wood

For added stability, staple the coco mat to the wood along the borders.

You should now have a wooden letter where the front is covered with the coco mat.

Step 5: Add Plants and Wait - Moss Letter

For the moss letter:

- spray the coco mat with the water bottle to wet it

- wash the moss, then blend it with the yoghurt in the kitchen blender, adding a bit of water if the solution is too thick

- for a 50cm x 60cm letter, I used two handfuls of moss and about 90g of yoghurt

- spread the moss / yoghurt solution on the mat

- keep in a shadowy place and spray regularly

- wait 2-3 weeks until the moss has grown

(It didn't really work well for me, I think the weather was too hot and dry)

Step 6: Add Plants and Wait - Cress Letter

For the cress letter:

- mix the fertilizer with water in the spray bottle, making sure to follow the instructions on the fertilizer package

- spray the coco mat with the water / fertilizer to wet it

- sprinkle on about 2/3rd of the cress seeds. You'll need the remainder to fill in empty spots later.

- optionally sprinkle with vermiculite and spray with water to keep it wetter

- protect a table with a plastic garbage bag and keep the letter, horizontal, on it. To avoid the wood getting all nasty, you can place it on cups or cans so it doesn't lie in the run-off water.

- keep away from direct sunlight.

Congratulation, you have a new annoying pet that needs to be watered all the time. Carefully spray with water multiple times a day, especially the borders as they tend to dry out. I've found it beneficial to shower the whole thing once a day in cold, drizzly water, turning the shower almost all the way down so it doesn't shower away the seeds. If the weather is rainy and overcast, you can also place the letter outside, the cress will love it. Every day, check the germination process and if you see a spot that didn't get enough seeds, just sprinkle on some more.

The photo at top is the letter after about 4 days. It should be ready for use in about 7-10 days total.