I came up with this project after my cat started chewing on all of my house plants. I used to buy him cat grass from my local farmer's market, but they started to get really expensive. ($9 for a 3x3 pot) So I decided to put my 3d printer to use and make a cheaper alternative using some stuff I had around the house. I'll be growing some cat grass (Barley) and some catnip for my little plant killer.
Step 1: Materials Needed
To start, you will need the following materials:
These items can be found at any Walmart
- - 1x Aquarium air pump - Found in the pet area
- - 1x 8 ft Length air tube - Found in the pet area
- - Small air-stones - You should ideally use small round air-stones, but I happened to have a few spare 4 inch air-stones - Found in the pet area
- - Mason jars with a regular sized mouth - The 3d file can only fit on regular mouth jars, not the wide mouth.
- - Cat nip seeds/Cat grass seeds (barley)
- - Large bowl
- - 1 Gallon distilled or Reverse Osmosis water
You will also need:
- Coconut fiber pith or rock wool which you can get at any hydroponics store. If you use the coconut fiber you will have A LOT of extra material.
- If you use rock-wool, you will need at least 1x 1-inch cubes as well as a few (handful) hydroton pebbles.
After germination you may also need:
- 1x Digital pH meter of pH test kit (fluid test)
- Liquid nutrients (ex. General Hydroponics)
Finally, you will need
- 1x -3d printed lid
Lid 3d print settings:
I printed the lid with Yellow 1.75mm ABS on a .4mm nozzle
- Layer Height: 0.2mm
- Shells/perimeter: 3
- Top/Bottom solid layers: 4
- Infill: 20%
- Skirt outlines:2
- Skirt Layers: 120 (Helps prevent warping/de-lamination at the base of the print)
- Print speed 60mm/s
The model may appear really small, if that is the case, scale it up by 10. I think it may be an issue with .obj files. Unfortunately Maya LT doesn't support .STL exports.
I've included the .STL of the lid that is properly scaled. (Thank you Blender!)
Step 2: Coconut/Rockwool Setup
For coconut fiber:
1. Remove the plastic packaging
2. Place the cube in a large bowl and add 1/4 of a gallon of water. The cube will absorb this water and swell up to about twice its original size. This will take about ten minutes so set aside and proceed to step 3.
For rock-wool cubes:
1. Remove cube from plastic packaging and remove the paper around the cube.
2. Fill a large bowl with enough water to soak 1-2 rock wool cubes.
3. Use a digital pH meter and test the water. You want the pH to be around 5.5. To lower the pH add a drop of lemon juice to the water and stir. Take the pH reading again and repeat until you get around 5.5.
4. Once you have the water at ~ 5.5 pH, place the rock wool cubes in the water and let soak for 1 hour.
Step 3: Prepare Lid and Jar
- Take the end of the air tubing and feed it through the small hole on the side of the lid. It will be a tight fit so you may need to use some needle nose pliers to help feed/pull it through. Feed about 5-6 inches through.
- Next feed the same end through the mesh at the bottom of the lid. Again this will be a tight fit, so you may need some pliers.
- Make sure you have enough air tube so that it goes at least 1/2 into the jar.
- Attach your air stone to the tube
- Screw the lid onto the jar. Be sure not to over tighten the lid.
- Measure out approximately 14-16 inches (depends on how far the jar will be from the air pump) of air tubing from the lid and cut the tube.
- Finally fill the jar almost to the top with distilled/Reverse osmosis water.
Step 4: Prepare Growing Medium and Add Seeds
If you are using coconut fiber:
By now your coconut fiber should have finished expanding.
- Take a chunk and break it up into small bits and place it in the bottom of the lid. Don't worry if some falls into the water, it won't have any effect on the plants.
- You want to put enough on the bottom to cover the holes. This will keep any seeds from falling in the water.
- Once you have the bottom covered, you can start sprinkling your seeds on the coconut fiber.
- If you want, you can add another thin layer of coconut fiber on top of the seeds.
If you are using rock wool:
- Take a rock wool cube and shred it into small chunks and lay on the bottom of the lid. You want to use enough to cover the holes on the lid.
- Then sprinkle your seeds on top of the rock wool.
Step 5: Let It Rip
After you set your seeds, plug your air stones into the air pump and turn it on.
Now you have your very own 3d printed desktop hydroponic system! And, if you're like me, you've got a very happy cat!
After your seeds sprout, you can add some hydroponic nutrients to the jars to keep your plants healthy. If you do, be sure to follow the directions on the nutrient bottles.
If you used rock wool
You can place some hydroton (clay pebbles found at hydroponic stores) on top of the rock wool to give the plants some support when they grow top heavy.
These pictures are the result after 5 days. The cat grass (barley) grew remarkably fast. The cat nip took a little longer to sprout. The round lid with the cat grass was the first lid prototype. I decided to go with the faceted lid as the final model because the round one was rather difficult to remove from the jars.