Making pots for plants may seem like a daunting task, but it really isn't all that hard! For the Instructables Gardening Contest 2019, I will show you how to make concrete plant pots by using a potato to shape them and silicone to make a mold. Also, each pot will cost only around 2 cents in concrete to make. The short animated video above will show the basic concept of what we are doing a little better. :)
Let's get into it!
Step 1: What You Will Need:
White Potatoes (you can use any kind but make sure that it is large enough) (1)
Silicone Molding Putty (.5 lbs)
Concrete or Cement
Deposable Cups (2)
A Kitchen Knife
A Mixing Stick (1)
Step 2: Cutting the Potato
To start off we need to cut the potato in the desired shape for our pots. Start off by cutting the potato in half. One large potato should be large enough for two pots. Take one of the halves and cut the other rounded side off. This will become the bottom of our pot.
Now that we have created the basic slab shape for our pot, the rest of this process is up to your liking. I went for a faceted looking design, but if you want you can go for a more rounded look. The one thing to keep in mind is not to make any angles that are too aggressive or steep. This will help us later on when trying to remove the potato from the silicone.
Step 3: Finishing the Design
Now that we have the basic shape for out planting pots we can start to carve out the hole where our plant will sit. to fo this, I used a 1/4 teaspoon measure. Because these pots are small, we need to use a smaller and more accurate tool. I started with a knife, cutting the circle about 1/2 inch deep. Next, I went in with the teaspoon measure to finish hollowing the potato. Make sure to make the walls of the pot at least 1/4 inch thick to keep the plant pot stronger.
Let's make the mold!
Step 4: Silicone: Making the Mold
Now that we have prepared the potato, we can move on to making the mold. We will be using silicone mold putty because it is easier to work with than liquid silicone and is much less messy than liquid silicone.
Here is the silicone I used: https://www.michaels.com/amazing-mold-putty-kit/10...
If the silicone seems expensive, keep in mind that you can reuse the mold many times.
To hold the silicone and to make the overall shape of the mold, I used a disposable paper cup. You can probably use a non-disposable cup, but you make need to cut the cup if the silicone won't release.
We need to place the potato cavity side down. This is the best orientation because then the actual cavity of the pot will be transferred into the silicone. If using a silicone putty like the one I linked above, you will need to mix part A and part B together to start the curing process. Keep in mind that the work time for this type of silicone is around 3-5 minutes. Make a ball of silicone that is large enough to fill the cavity of your potato. Pack the silicone putty tightly and try to avoid air bubbles. Place a thin layer of silicone on the bottom of the cup and place the potato with the silicone-filled-cavity side down. Use the rest of your silicone to fill around the potato. Fill the silicone until it is flush with the bottom of the pot.
From there, let the silicone set for at least 20 minutes. Then, take the potato out, and the mold is complete!
Step 5: Casting the Concrete and Finishing
This part is very simple. We start by mixing our concrete according to the package that you choose. Pour the concrete into your mold in a slow and in as thin of a stream as you can. This helps reduce air bubbles. Tap the sides of the mold, and lightly tap the mold on the working surface to further remove air bubbles.
Let the concrete set for the needed time (It took an hour for the concrete I used).
Once set, carefully remove the pot without ripping the silicone.
We are almost done but if you want we can finish the plant pot with some fine grit sandpaper. To make the pot more water resistant, I took a candle and rubbed the wax onto the pot. These steps are optional, but make the pot look better.
We are done!
I really hope that you enjoyed this instructable and that it is helped you.
Thanks for reading to this point!